The findings of a clinicopathological and biochemical study of epidermal cysts and a review of the relevant literature are presented. A punctum was found in 40% of 34 epidermal cysts that were studied in detail. The findings of the histological study were in favour of the punctum being the orifice of an obstructed hair follicle from which at least a proportion of the epidermal cysts are likely to develop. The biochemical analysis of the contents of the cysts revealed a very low protein and lipid content, thus ruling out any "sebaceous' contribution. Bacteriological study of clinically inflamed cysts showed that inflammation in these lesions was usually aseptic unless there was a communication between the cyst cavity and the exterior.