Despite the availability of free or low-cost public sector human immunodeficiency virus (HIV) health-care services, important inequities in utilization exist. This study examined two measures of compliance with HIV medical care: attendance of scheduled outpatient visits and use of the emergency room. Clients of two public HIV outpatient clinics were followed from time of health-care initiation to either death or the end of the study. The association of race, sex, age, and injection drug use (IDU) with these measures were examined in multivariate logistic regression. Models were adjusted for disease staging at time of entry and for length of follow-up time in clinic. Of 1824 clients followed, 15% failed to attend scheduled visits and 18.1% had at least one emergency room visit. Clients who missed visits were more likely to be African American, to have a history of IDU, and to have a CD4 cell count < 500/mm3 or an acquired immunodeficiency syndrome (AIDS)-defining opportunistic infection at entry. They were also more likely to have > or = 12 months of follow-up time in the HIV clinic, but were less likely to have entered into health care from an early intervention clinic. Clients who had at least one emergency room visit were more likely to be African American, female, IDU, and under 22 years of age; these clients were also more likely to have entered with CD4 < 200/mm3 or with an opportunistic infection, and to have > or = 12 months of follow-up in the clinic.(ABSTRACT TRUNCATED AT 250 WORDS)