We report a case of B-cell lymphoma primarily involving the skin in a 12-year-old boy. The histopathologic findings were compatible with those of small lymphocytic type of non-Hodgkin's lymphoma. A cutaneous lesion was the sole manifestation of his disease without any other organ involvement. Immunophenotypic studies and immunoglobulin gene rearrangement with Southern blot analysis determined its lineages and monoclonality with result of B-cell lineage neoplasm, i. d. CD20⁺, C1323⁺, CD35^- and rearranged band on JH probe. We treated him with surgical excision and CVP regimen of chemotherapy (cyclophosphamide, vincristine, prednisolone). There is no recurrence or metastasis during the last six months.