The case history is reported of a 59-year-old man with a locally symptomatic sacral chordoma. During treatment with radical radiotherapy, he developed gas gangrene, which proved rapidly fatal. At post-mortem examination there was evidence of local invasion of the rectum by the tumour and extensive gangrenous myonecrosis (gas gangrene) involving the pelvic tissues and left leg. An unexpected finding was the presence of histologically distinct bilateral renal cell carcinomas. Neither gas gangrene nor renal cell cancer has been reported previously in association with sacral chordoma.