Eighteen patients with chronically recurrent vaginal candidosis showed low T-lymphocyte counts twice as frequent as a control group of 55 women. The patients were treated with azoles locally and lymphocyte stimulating pentapeptide thymopentin. The prolongation of disease-free intervals and a cure was mainly seen in the patients with low T-cell values before therapy. In vitro-proliferation assays upon stimulation with Candida albicans bore no correlation with the course of the disease. We suspect a failure in the co-operation of the immune cells, caused by differing strong responses to the Candida albicans stimulation.