The use of combination antiretroviral therapy for HIV infection is a rapidly changing field. To assess the impact of recent studies on prescribing patterns, two surveys of 21 high HIV caseload Australian GPs were undertaken in June 1996 and June 1997 to plot changes in the choice of combination antiviral therapy. Of the 17 GPs who responded to the survey in each year, the number of HIV-infected patients seen at their practices were estimated to be 5,061 in 1996 and 5,912 in 1997. In 1996, 40% of their patients were estimated to be on antiretroviral therapy compared to 60% in 1997 (p < 0.05). In 1996, most GPs preferred using dual combination therapy (59%); whereas in 1997, triple combination therapy was preferred (82%). Between 1996 and 1997, there was a significant change by high caseload Australian GPs in the choice of antiretroviral drugs with many combinations being preferred prior to presentation of efficacy data for those combinations, or recommendation through national guidelines.