Sample size to achieve 80% power to detect a difference in failure rates of 20% and 10% (20% in the nystatin group and 10% in the GV groups) is 155 in each group.This assumes an HIV positivity of 50%. As a drop out rate of 20% is expected from death (in some HIV infected patients) or failure to attend for follow up, a sample size of 186 per group is to be recruited. This gives an overall number to be enrolled of 558 patients.