Plavšić was a member of the Serbian Democratic Party (SDS).
She was the first female member of the Presidency of the Socialist Republic of Bosnia and Herzegovina, serving from 18 November 1990 until April 1992 after having been elected in the first multi-party elections in 1990 in Bosnia and Herzegovina.
From 28 February 1992 to 12 May 1992, Plavšić became one of the two acting presidents of the self-proclaimed Serb Republic of Bosnia and Herzegovina.
Thereafter she became one of two Vice-presidents of the Republika Srpska and from circa 30 November 1992 she was a member of the Supreme Command of the armed forces of the Republika Srpska.

Plavšić declared that "six million Serbs can die so that the remaining six million can live in freedom" and considered the ethnic cleansing carried out against non-Serbs during the war to be a "natural phenomenon".
In July 1993, in a statement to Borba, Plavšić reportedly claimed that Bosnian Serbs are ethnically-racially superior to Bosnian Muslims and claimed that: 
The Serbs in Bosnia, particularly in the border areas, have developed a keen ability to sense danger to the whole nation and have developed a defense mechanism.
In my family they used to say that the Serbs in Bosnia were much better than Serbs in Serbia [...] and remember, the defense mechanism was not created through a short period of time; it take decades, centuries [...] I am a biologist and I know: most capable of adapting and surviving are those species that live close to other species from whom they are endangered.

In 1994 Plavšić stated that she and other Serbian nationalists were unable to negotiate with the “”Bosniaks”” due to genetics:
It was genetically deformed material that embraced Islam.
And now, of course, with each successive generation it simply becomes concentrated.
It gets worse and worse.
It simply expresses itself and dictates their style of thinking, which is rooted in their genes.
And through the centuries, the genes degraded further.

 
This statement by Plavšić, which equated a specific ethnic group with a disease or illness, has been compared to how the Nazis identified the Jews.

The Dayton Agreement, signed in 1995, banned the then President of Republika Srpska Radovan Karadžić from office and Plavšić was chosen to run as the SDS candidate for President of the Republika Srpska for a two-year mandate.

Vojislav Šešelj, at the Milošević trial, described Karadžić's motives for nominating her.

She held very extremist positions during the war, insufferably extremist, even for me, and they bothered even me as a declared Serb nationalist.
She brought Arkan and his Serb Volunteer Guard to Bijeljina, and she continued to visit him after their activities in Bijeljina and the surrounding area [...] Radovan Karadzic [...] believed her to be more extreme than himself in every way.
He thought that the Western protagonists who tried eliminate him at any cost would have an even greater problem with her [...] Radovan Karadzic believed that she would continue to occupy her patriotic positions until the end.
However, several months after she was elected, Biljana Plavsic changed her political orientation by 180 degrees under the influence of some Western protagonists and changed her policies completely.

She severed her ties with the SDS and formed Srpski narodni savez (Serbian People's Alliance of the Republika Srpska), and nominated Milorad Dodik, the then member of the National Assembly of the Republika Srpska whose SNSD party had only two MPs, for Prime Minister.
She lost the 1998 election to the joint candidate of the SDS and the Serbian Radical Party of the Republika Srpska Nikola Poplašen.
She was a candidate of the reform "Sloga" coalition.
During her time in prison, she released a book called "Witnessings" (Svjedočenja), revealing many aspects of the political life of the war-time Republika Srpska.
In 1998, Plavšić rewarded Momčilo Đujić, a Chetnik commander and collaborator, with an honorary award.
Plavšić was a member of the Serbian Democratic Party (SDS). She was the first female member of the Presidency of the Socialist Republic of Bosnia and Herzegovina, serving from 18 November 1990 until April 1992 after having been elected in the first multi-party elections in 1990 in Bosnia and Herzegovina. From 28 February 1992 to 12 May 1992, Plavšić became one of the two acting presidents of the self-proclaimed Serb Republic of Bosnia and Herzegovina. Thereafter she became one of two Vice-presidents of the Republika Srpska and from circa 30 November 1992 she was a member of the Supreme Command of the armed forces of the Republika Srpska.
Plavšić declared that "six million Serbs can die so that the remaining six million can live in freedom" and considered the ethnic cleansing carried out against non-Serbs during the war to be a "natural phenomenon". In July 1993, in a statement to Borba, Plavšić reportedly claimed that Bosnian Serbs are ethnically-racially superior to Bosnian Muslims and claimed that: 
The Serbs in Bosnia, particularly in the border areas, have developed a keen ability to sense danger to the whole nation and have developed a defense mechanism. In my family they used to say that the Serbs in Bosnia were much better than Serbs in Serbia [...] and remember, the defense mechanism was not created through a short period of time; it take decades, centuries [...] I am a biologist and I know: most capable of adapting and surviving are those species that live close to other species from whom they are endangered.
In 1994 Plavšić stated that she and other Serbian nationalists were unable to negotiate with the “”Bosniaks”” due to genetics:
It was genetically deformed material that embraced Islam. And now, of course, with each successive generation it simply becomes concentrated. It gets worse and worse. It simply expresses itself and dictates their style of thinking, which is rooted in their genes. And through the centuries, the genes degraded further.
 
This statement by Plavšić, which equated a specific ethnic group with a disease or illness, has been compared to how the Nazis identified the Jews.
The Dayton Agreement, signed in 1995, banned the then President of Republika Srpska Radovan Karadžić from office and Plavšić was chosen to run as the SDS candidate for President of the Republika Srpska for a two-year mandate.
Vojislav Šešelj, at the Milošević trial, described Karadžić's motives for nominating her.
She held very extremist positions during the war, insufferably extremist, even for me, and they bothered even me as a declared Serb nationalist. She brought Arkan and his Serb Volunteer Guard to Bijeljina, and she continued to visit him after their activities in Bijeljina and the surrounding area [...] Radovan Karadzic [...] believed her to be more extreme than himself in every way. He thought that the Western protagonists who tried eliminate him at any cost would have an even greater problem with her [...] Radovan Karadzic believed that she would continue to occupy her patriotic positions until the end. However, several months after she was elected, Biljana Plavsic changed her political orientation by 180 degrees under the influence of some Western protagonists and changed her policies completely.
She severed her ties with the SDS and formed Srpski narodni savez (Serbian People's Alliance of the Republika Srpska), and nominated Milorad Dodik, the then member of the National Assembly of the Republika Srpska whose SNSD party had only two MPs, for Prime Minister. She lost the 1998 election to the joint candidate of the SDS and the Serbian Radical Party of the Republika Srpska Nikola Poplašen. She was a candidate of the reform "Sloga" coalition. During her time in prison, she released a book called "Witnessings" (Svjedočenja), revealing many aspects of the political life of the war-time Republika Srpska. In 1998, Plavšić rewarded Momčilo Đujić, a Chetnik commander and collaborator, with an honorary award.
Biljana Plavšić