The most common disease of the pilosebaceous follicle is acne vulgaris. The primary detectable pathologic defect in acne is abnormal keratinization of the follicular epithelium, resulting in a retention hyperkeratosis. The primary lesion produced by this process, the comedo, ist the precursor of most other acne lesions. These include inflammatory papules, pustules and nodules. Treatment principles are directed against known pathogenic factors. The major topical modalities that are currently being used include tretinoin, benzoyl peroxide and topical antibiotics. Benzoyl peroxide is a powerful antibacterial agent. Topical erythromycin and clindamycin appear to have equivalent efficacy. A major treatment advance has been heralded by the use of oral 13-cis retinoic acid (isotretinoin) in the management of patients with severe nodulocystic acne, acne conglobata and acne fulminans. Isotretinoin is teratogenic and should not be given to women of childbearing age.