A 72-year-old female was found to have a large primary mesothelioma of the right flank musculature. She was not felt to be surgically resectable and was treated with 3D-conformal radiotherapy alone to a total dose 70 Gy. She had a complete response with no evidence of local progression when two years after treatment imaging revealed lung metastases, confirmed on biopsy. The present case suggests that radiotherapy alone can provide sustained local control of mesothelioma.