Lymphangioma is a congenital malformation of the lymphatic system that expands into the surrounding tissues in a manner similar to a malignant tumor. Surgical excision has been the treatment of choice, but the results are often unsatisfactory due to incomplete resection, fluid collection and recurrences. Intralesional injection of OK-432(lyophilized incubation mixture of Group A Streptococcus pyogenes of human origin) was employed in treating 24 patients with lymphangiomas between 1992 and 1997. The method was used in 21 patients as a primary therapy, and in 3 patients for unresectable or recurrent cases as a secondary treatment. The results were excellent in 8 patients (33.3%), good in 7 patients (21.8 %) and poor in 7 patients (21.8 %). The side effects were fever under $39^{circ}C$ and local inflammation. However these symptoms subsided in a few days without serious sequelae. These results suggest that intralesional injection of OK-432 is safe and effective treatment for primary lymphangioma as well as a secondary therapy for unresectable or recurrent cases.