In the past 5 yr, an increased incidence of tuberculosis has been noted in the United States. Simultaneously, the population infected with human immunodeficiency virus-type I (HIV-I) and the number of cases of acquired immunodeficiency syndrome (AIDS) have increased. Selected areas of the United States have also reported increases in the frequency of drug-resistant isolates of Mycobacterium tuberculosis. Because our institution serves a population in which tuberculosis, AIDS, and drug resistant isolates of M. tuberculosis are frequently encountered, we sought to better define interrelationships among these factors by retrospectively reviewing the demographic, clinical, bacteriologic, and radiologic data for all adult patients in whom M. tuberculosis was isolated from a culture of respiratory-tract secretions during a 1-year period (June 1, 1988 to May 31, 1989). Two hundred forty-six patients were thus identified; 66.5% were U.S. born blacks, and 62.6% were 17 to 40 yr of age. Risk factors for HIV infection were present in 106 patients. The overall resistance rate (one or more drugs) = 30.9%, with primary resistance = 22.6% (35 of 155) and secondary resistance = 49.2% (29 of 59). In addition, 12 resistant isolates were found in 32 patients whose prior treatment status was indeterminate. Of the resistant isolates, 56.6% (43 of 76) were multiply resistant. Isoniazid resistance was noted in 90.7% (69 of 76) and rifampin resistance was noted in 50% (38 of 76) of the resistant isolates. No significant differences in the overall frequency of resistance were noted in patients at risk for HIV infection compared with those without these risks.(ABSTRACT TRUNCATED AT 250 WORDS)