The paper presents a single case study of the treatment of primary encopresis in a 6 year old boy. The boy had never had regular bowel movements, suffered from retention for periods of 4–5 days, and soiled himself when he finally passed a bowel movement. The subject was treated using behavioural and cognitive techniques, and the progress was evaluated using a single subject design. The findings revealed that the intervention succeeded in stopping the boy's soiling and retention and in his achieving regular bowel movements. Two follow-up interviews after six and twelve months demonstrated that the improvement had persisted. The results suggested that the behavioural therapy package constituted an effective means for the treatment of encopresis.