Two infants with solitary mastocytoma were treated with 5 mg/kg/day of tranilast [N-(3',4'-dimethoxycinnamoyl)anthranilic acid], a mast cell stabilizing compound extracted from Nandina domestica. Tranilast was administered orally in three divided doses. In one infant, a topical corticosteroid was also applied in combination with the oral tranilast. Patients experienced symptomatic relief, and nodules resolved almost completely after eight weeks of treatment. Tranilast therapy was continued for six months. No relapses were observed after discontinuation of therapy. We speculated that tranilast not only inhibited mast cell degranulation but also reduced the number of mast cells.