Scalp ringworm or tinea capitis has become an increasingly important public health issue in the past decade in Great Britain. Recently, certain dermatology departments in London have seen a large increase in tinea capitis in all its forms. The aim of this paper is to present the detailed analysis of a cohort of 277 patients with tinea capitis seen during a 2-year period together with the latest local figures of tinea capitis cases from an inner city paediatric dermatology service. Methods Demographic, clinical and laboratory data were collected prospectively over 2 years from all cases of ringworm in patients seen in a paediatric clinic specially set up for scalp problems. Sixty-two per cent of 277 cases of scalp ringworm were caused by Trichophyton tonsurans, occurring mainly (91%) in patients with Afro-Caribbean hair type, more often in boys (68%), and in the 3-8 year olds (70%). Only 7% of the patients had received appropriate treatment with oral griseofulvin. An additional 156 cases from the general paediatric dermatology clinic showed 91%T. tonsurans infections. The prevalence of scalp ringworm appears to be reaching epidemic proportions in certain areas that include south-east London. The clinical problem is not yet well recognized by local general practitioners.