For many years the exact nature of the pathophysiology of seborrhoeic dermatitis and dandruff was in doubt. Different schools of thought debated whether Pityrosporum yeasts were of primary pathogenic significance or a secondary phenomenon, with epidermal hyperproliferation as the primary pathology. Although effective therapy in seborrhoeic dermatitis and dandruff has for a long time been based on compounds whose only common link was antipityrosporal activity, proof of this relevance was lacking until the introduction of effective antifungal drugs, in particular ketoconazole. This article charts the swing of opinion towards the primary pityrosporal aetiology of seborrhoeic dermatitis and dandruff, reviews the evidence that antipityrosporal activity is the common link to various compounds which benefit these conditions, and compares the efficacy of these substances in treatment.