We have designed a combined method using a lipid-absorbent tape and skin surface stripping to evaluate the relationship between the follicular sebum excretion rate and the microanatomy of the follicular duct openings. Many sebaceous follicles appear quiescent in normals and with acne patients. Most of the large spots on the lipid-absorbent tape are due to the confluence of smaller ones. 'Open' comedones in acne are functionally closed.