The municipality was created in 1970 as the result of a kommunalreform ("Municipality Reform") that combined a number of existing parishes:
Hvalsø Parish
Kisserup Parish
Såby Parish
Særløse Parish
On January 1, 2007 Hvalsø municipality ceased to exist as the result of Kommunalreformen ("The Municipality Reform" of 2007).
 It was merged with Bramsnæs and Lejre municipalities to form the new Lejre municipality.
 This created a municipality with an area of 240 km² and a total population of 25,971 (2005).
The municipality was created in 1970 as the result of a kommunalreform ("Municipality Reform") that combined a number of existing parishes:
Hvalsø Parish
Kisserup Parish
Såby Parish
Særløse Parish
On January 1, 2007 Hvalsø municipality ceased to exist as the result of Kommunalreformen ("The Municipality Reform" of 2007).  It was merged with Bramsnæs and Lejre municipalities to form the new Lejre municipality.  This created a municipality with an area of 240 km² and a total population of 25,971 (2005).
Hvalsø