In order to estimate the importance as a public health problem of skin diseases, we investigated the prevalence and severity of skin diseases in a representative sample of children in Mali. 1817 children were randomly selected in 30 clusters by probability-proportional-to-size sampling in Koulikoro region. The mean prevalence (+/- 2 SD) of skin diseases was 34 +/- 4%. The most frequent dermatoses were pyoderma (12.3 +/- 1.6%), tinea capitis (9.5 +/- 2.5%), pediculosis capitis (4.7 +/- 1.4%), scabies (4.3 +/- 1.5%), and molluscum contagiosum (3.6 +/- 1%). The most troublesome dermatoses were scabies and severe pyoderma. Pyoderma was the only dermatosis associated with poor individual or household hygiene. Public health services were little used by the population for skin diseases, probably because of the lack of an adequate response by the services and the high cost of treatment. The high prevalence and the severity of many of the lesions, and the discomfort caused, make pyoderma and scabies a significant public health problem in Mali.