Can I apply for a PhD in the United States with a 3-year undergraduate degree from Italy? I'm currently studying in Italy for an undergraduate degree which is 3 years long (standard BSc in Computer Science). Since I'm also U.S. citizen, I was thinking it would be interesting to perhaps apply for a PhD in the states since it doesn't require a master's degree (it does in Italy). Is this possible or are the systems inherently different?
Many universities in the US have policies that prevent students with a 3 year bachelor's degree from applying for graduate admission.  To get into one of those programs you would have to complete at least one more year of study before being admitted to the graduate program.