The long-term outcome of 106 patients treated for hydrocele with the sclerosing agent sodium tetradecyl sulphate was examined. In a questionnaire distributed at a mean time of 40 months after therapy 83/86 (96%) of the eligible patients responded and 95% of them were satisfied with the treatment and its long term results. The treatment associated pain was evaluated on a visual analogue scale (0-10) the mean pain score was found to be 1.8 and the mean duration of the pain 2.4 days. When all hydroceles were considered the overall success rate was 88%. Side-effects were minor apart from two patients (1.9%) with diabetes mellitus who had an intense inflammatory reaction necessitating orchidectomy after sclerotherapy.