Two hundred and twenty-two women with advanced cancer of the breast were asked to complete two previously validated self-assessment questionnaires (Hospital Anxiety and Depression Scale (HADS) and the Rotterdam Symptom Checklist (RSCL) in order to determine the prevalence and persistence of affective disorders in this group of patients. Fifty-six (27%) of 211 women who completed the HADS and 33 (22%) of 204 who completed the RSCL rated as probable cases of an anxiety state and/or depressive illness. One hundred and fifty-five patients completed the questionnaires again 1-3 months later. Twenty-one (13%) were persistently anxious or depressed as judged by the HADS compared with 14 (10%) on the RSCL. When both questionnaires were considered together, approximately one third of patients had scores suggestive of an affective disorder and in one third of these it was persistent. Only 30 patients (43% of cases) were detected as 'cases' by both questionnaires and this finding warrants further investigation.