Paykel's Clinical Interview for Depression (CID), an observer-rated scale, and Kellner's Symptom Questionnaire (SQ), a self-rating inventory, were administered to twenty-six patients with breast cancer: 1) the day prior to discharge after mastectomy or lumpectomy, 2) after six months, during a follow-up outpatient visit. There were no significant changes in depression and anxiety (except for self-rated anxiety) and, indeed, there were very high test-retest correlations. Observer and self-rated assessments were significantly related, and these correlations improved on outpatient follow-up. DSM-III-R diagnoses of affective illness (mood and anxiety disorders) based on pre-established cut-offs of the CID, showed considerable stability, particularly as to major depressive illness.