We report a case of Fournier's gangrene. An 83-year-old man underwent biopsy of left inguinal tumor as an outpatient. Pathological diagnosis was malignant lymphoma (diffuse large cell type). Three weeks later, he developed reddened scrotal swelling accompanied with high fever (> 39 degrees C). On admission, antibiotic chemotherapy was initiated. Although his general condition was improved, scrotal necrosis had developed. A computed tomography scan demonstrated thickened subcutaneous tissue over the left lumbar region. Excision of necrotic tissue and sequential irrigation using povidone iodine liquid were effective. The patient then underwent chemotherapy for malignant lymphoma at the internal department. Nine months after the operation, the scrotal skin had completely recovered.