The current study examines sex differences in 183 male and 141 female patients presenting for care of HIV disease at an inner city hospital infectious disease clinic. Females (43%) were found to be less likely to have a history of illicit drug use (relative risk = .77, p < .01) and more likely to have become infected heterosexually (relative risk = 2.38, p < .01). However, a significant number of women reported both intravenous drug use (IVDU) and heterosexual exposure to an IVDU partner which complicates the analysis of the risk factors. Women sought testing because they knew that their sexual partners were HIV-positive (relative risk = 2.88, p < .01) Median CD4 counts at entry were significantly different (females = 340, males = 246; p < .01). Women were less likely to contract tuberculosis, the only infection which presented with a sex difference (relative risk = .38, p < .01) and to have previously had an AIDS defining infection (relative risk = .37, p < .01). Women took longer to progress to AIDS (42 vs. 19 months; p < .05). Survival of patients with AIDS was 51 months for females and 54 for males (p > 0.9). It did appear that the effect of a lower CD4 cell count on risk for death was magnified in patients who acquired their disease through heterosexual transmission. Women presented with higher CD4 counts, were more aware of their risk factors and fared better, with respect to progression to AIDS, than the men. The study underscored the impact of heterosexual transmission of the virus in women as well as the affect of this risk factor on disease progression. Hopefully, this information will initiate further studies on sex differences which will guide interventions and policy development.