Twenty patients with scalp seborrhoeic dermatitis were treated twice weekly with ketoconazole 2% shampoo for 4 weeks. Clinical assessment, culture for P. ovale on Dixon broth and lipid measurement at two places were made before treatment and after 2 and 4 weeks. Significant improvement of the severity of seborrhoeic dermatitis (p < 0.001) and negative mycological tests by 19 (95%) of patients were observed. The scalp lipid content remained unaltered in 11 patients with an initial lipid value over 220 micrograms/cm2 but increased in those with lower initial values. This is probably due to the improvement of sebum delivery onto skin surface as a result of the elimination of the follicular occlusion.