Histological sections from 50 patients with clinical stage Ib to stage IIb squamous cell carcinoma of the cervix, initially treated by radiotherapy and followed by Wertheim hysterectomy, were reviewed and stained for mucin. The tissues from 17 (34%) of the patients contained no residual carcinoma. Mucin production was demonstrated in tumour tissue from 18 (55%) of the patients with residual tumour, none of who died of disease during the 5 to 10 years of follow up. Two patients who died of recurrent carcinoma had no mucin production in the post-irradiated tumour tissues. The presence of mucin in irradiated carcinoma of cervix seems to infer a better prognosis and this may prove useful in the follow-up of irradiated carcinomas.