Erythema multiforme (EM), a cutaneous or mucocutaneous disorder, occurs primarily in young adults. To evaluate the precipitating factors, clinical courses, and treatment of this disease in children, 30 cases aged from 1 month old to 15 years of age were studied retrospectively from Jan 1988 to Aug 1998. Twenty-three cases were diagnosed as minor type; the other 7 were of major type (Stevens-Johnson syndrome). Mycoplasma infection was identified in 4 patients, and adenovirus in one patient with EM minor. Cytomegalovirus was found in one EM major patient. Anticonvulsant administration before the skin lesions were recorded in 5 EM major patients and 2 EM minor patients. All cases received supportive treatment during admission. Besides, 6 of 7 patients with EM major, and 11 of 23 EM minor (Group A) received systemic corticosteroid at a dose equal to prednisolone 1-2 mg/kg/day for 3-14 days. One EM major patient and 11 patients with EM minor (Group B) received supportive care only. One EM minor patient with acute idiopathic thrombocytopenia purpura was treated with intravenous immunoglobulin. The mean duration of course of EM minor was 11.8 +/- 2.9 days, and it was 25.1 +/- 9.8 days for EM major. No mortality and no sequelae were noted. The average disease course and hospitalization time were not significantly different between Group A and B: (11.4 +/- 3.1 days vs 12.4 +/- 2.9 days, p = 0.45); (5.4 +/- 2.0 days vs 6.3 +/- 3.1 days, p = 0.47). This study demonstrated that infections, especially mycoplasma, and anticonvulsants play important roles in childhood EM. The skin lesions of EM minor subsided within 2 weeks, and EM major recovered completely within 6 weeks. Systemic corticosteroid may be beneficial to EM major, but probably is unnecessary for patients with EM minor.