Ten patients receive nevirapine daily for 12 weeks. After 12 weeks of therapy, patients in whom resistance was not evident at week 4 and who have an adequate safety profile continue receiving nevirapine for an additional 12 weeks. Clinical and immunological assessments are performed at weeks 4, 8, 12, 16, 20, and 24. Virological assessments are performed at week 24 only. If 50 percent of patients develop resistance at any time, the study is discontinued.