An interim analysis of the first 61 patients showed that a clinical and statistical difference exists between the occurrence of HIV-1 NNRTI resistant mutations in the single dose nevirapine only arm (50%) and the two other combination arms (9%). These findings partially answered the objectives outlined in the initial objectives. Consequently enrolment onto the single dose nevirapine arm was terminated. The objective of the trial was modified to compare whether either the 4 or the 7 day combination of ZDV+3TC and nevirapine would result in any significant reduction in the incidence of nevirapine resistance.