Approximately 28% of HIV-infected people in treatment in the United States report using illicit drugs. Illicit drug users have poorer course of HIV disease than non-drug users, which is thought to be due to their irregular use of HIV medical services. We examined associations between type (cocaine versus opioids) and pattern of drug use (drug use at baseline, 6-month follow-up, both periods, and nonuse) and health care utilization for a large sample of HIV-infected individuals drawn from a multisite project that evaluated the impact of medical outreach interventions for populations at risk of poor retention in HIV care. Across all types and patterns of drug use, drug users were more likely to have suboptimal ambulatory care, miss scheduled appointments, use the emergency department, have unmet support services needs, and were less likely to take antiretroviral medications. Additionally, while people who started using drugs during the follow-up period and consistently used drugs across both periods differed from nonusers on missed appointments (odds ratio [OR] = 2.20 for starters versus nonusers, OR = 2.92 for consistent users versus nonusers), emergency department use (OR = 4.93 for starters versus nonusers, OR = 2.24 for consistent users versus nonusers), and antiretroviral medication use at follow-up (OR = 0.23 starters versus nonusers, OR = 0.19 for consistent users versus nonusers), those who stopped using drugs after the baseline period did not differ from nonusers. We conclude that health care utilization is poorer for people who use illicit drugs than those who do not, and stopping drug use may facilitate improvements in health care utilization and HIV outcomes for this population.