Fifty eight children with Langerhans cell histiocytosis who were referred to this hospital between 1980 and 1987 were studied. Fourteen had single system disease, and 44 had multisystem disease, of whom 22 had vital organ dysfunction. A conservative approach to treatment was adopted, and when systemic treatment was indicated a short course of prednisolone was used first. Eight of the patients with single system disease required no treatment, while six received local treatment alone. Eight of the patients with multisystem disease did not require systemic treatment, 17 were given prednisolone alone, and 19 were given cytotoxic drugs. Of the 14 with single system disease 13 had no long term after effects. Eight of the patients with multisystem disease died, 24 had long term after effects, and 12 had none. Outcome was related to age and Lahey score. These results compare favourably with other series in which more aggressive approaches were used, and support our conservative approach to treatment.