SUMMARY.—The method of skin surface biopsy in which a cyanoacrylate adhesive is used to remove a coherent strip of stratum corneum, has been used to investigate aspects of epidermal function. The Sudan dyes were employed to demonstrate sebum in the hair follicle openings. Although increased quantities of Sudanophilic material were detected with increasing time intervals before sampling, it proved impractical to measure sebum secretion quantitatively by this method. Hydrolase activity in and around hair follicle orifices of the back, forehead and forearm were demonstrated, using enzyme histochemical methods for non‐specific esterase, acid phosphatase, leucine aminopeptidase and β‐glucuronidase activities. Specimens from the forehead and back were found to have stronger activities than those from the forearm. Apart from the vicinity of the follicular openings, non‐specific esterase activity was not normally found in the superficial stratum corneum, although scattered areas of activity were present in the deeper parts of the horny layer. Strong, non‐specific esterase activity was detected in skin surface biopsies from lesions of pityriasis lichenoides and, to a lesser extent, those of psoriasis. Mitochondrial enzyme activities were retained in parakeratotic scale from patients with psoriasis, pityriasis rubra pilaris and areas made parakeratotic after repeated removal of the stratum corneum, although not from the lesions of pityriasis lichenoides. The method also proved suitable for the demonstration of melanin granules, blood pigment and sweat glan