In Argentina there are no published data on the incidence of AIDS (ARM) and non-AIDS related malignancies (non-ARM) in the HIV positive population. Our aim was to establish the incidence of these malignancies at an ambulatory care center between 1997 and 2005. We describe 103 cases of malignancies, 73 out of them were ARM and 30 were non-ARM. There were no differences in terms of age, gender and proportion of patients on highly active antiretroviral treatment (HAART). Among those patients with ARM, simultaneous diagnosis of malignancy and HIV infection was more frequently seen (p <0.001) and the proportion of patients with AIDS was higher (p = 0.015). Among those patients with non-ARM the mean duration of HIV infection and HAART was higher (p = 0.038 and 0.002 respectively); also was higher the mean CD4 count nadir (p = 0.009), and CD4 count at the time of malignancy diagnosis (p <0.001). The incidence of ARM was 18 cases/1000 patients-year in 1997 and dropped to 3.1 cases/1000 patients-year in 2005 (p = 0.001). The incidence of non-ARM was always lower than ARM, and similar in each year. In conclusion, ARM were more frequent than non-ARM, but their incidence dropped significantly because of massive use of HAART, while non-ARM remained stable. The high proportion of simultaneous diagnosis of ARM and HIV infection should enable much earlier HIV diagnosis.