With an increasingly aged population, the number of patients requiring treatment for cardiovascular diseases will rise. Previous expectations of cardiac surgery in the over-seventies have been poor, with surgery being very much a last resort. We decided to test whether this was appropriate, and to determine whether the priority of surgery affected the outcome. Three hundred and six patients over the age of 70 were operated on in our unit in a 4 1/2-year period, 210 as elective operations and 96 as emergencies. Eighty-nine per cent were in NYHA class III-IV pre-operatively and half had other significant medical problems. Most (46%) underwent coronary artery surgery. The methods used were identical to those used for the younger patients in both operative approach and post-operative management. The overall mortality was 6.9%; 1.9% for elective procedures and 16.7% for emergencies (12.3% when catastrophic pathologies are excluded). However, the morbidity was not significantly different between the two groups and the length of post-operative ventilation and hospital stay were likewise not significantly different. Follow-up of the survivors showed no late deaths, and 87% were in NYHA class I and II. Of the others, 25 have required additional hospital admissions for associated cardiac problems. One required another invasive procedure (a PTCA), but none has required further surgery. The findings of low mortality for elective cardiac surgery in this age group are in agreement with other reports. If early referral prevents emergency surgery, it should be avidly pursued, in view of the improved outcome for elective surgery.(ABSTRACT TRUNCATED AT 250 WORDS)