p53 expression was assessed immunohistochemically in 24 'end stage disease' patients with squamous cell carcinoma of the head and neck, prior to selection for a chemotherapy trial. Twelve patients were assigned to each arm of the trial; cisplatinum arm or the cisplatinum and nifedipine arm. p53 expression was assessed using the CM-1 antibody in specimens from biopsies or surgically removed tissue at the time these patients were assessed as end stage disease. Sixty-six per cent had p53 positive nuclear staining but no correlation was found between p53 staining and age, sex, site of primary tumour, tumour stage, or site of the recurrence. Three patients responded to cisplatinum chemotherapy treatment, two of whom had p53 positive staining. p53 survival curves were calculated for these patients from the date they were assessed as 'end stage disease', p53 overexpression was found to correlate with a very poor clinical outcome (P<0.05). Survival curves for 109 head and neck patients calculated from the date the disease first presented showed no correlation with p53 expression.