Background: Previous Registry studies have reported that heart transplantation with older donor hearts is associated with a more than twofold increase in early mortality. Methods: An analysis of 77 consecutive patients undergoing heart transplantations at our institution between June 1988 and July 1994 was performed to assess the effect of donor age on mortality and morbidity. Recipients were grouped into those receiving hearts from younger donors (aged < 40 years, n = 60) and those receiving hearts from older donors (aged > 40 years, n = 17). Results: There were two deaths within the first 30 days in the younger donor group and no deaths in the other group. One-year survival rate was 95% and 100% for the 'younger' and 'older' groups, respectively. The mean recipient age of the younger donor group was lower (46 ± 14 years) compared with the older donor group (57 ± 7 years). Morbidity was compared between the two groups; the length of hospital stay (22.6 ± 15.8 days versus 21.3 ± 9.4 days), the graft ejection fraction at 1 week (64% ± 5% versus 62% ± 7%), and the mean number of rejection episodes within the first 3 months (0.79 versus 0.65) were not statistically different between the two groups. However, the incidence of chronotropic incompetence requiring permanent pacemaker implantation was significantly greater in the group who received older donor hearts (41.2% versus 10.3%, p < 0.05), independent of the ischemic time. Conclusions: This study shows that older donor hearts may be used safely in selected patients with excellent outcome, although there is an increased incidence of chronotropic incompetence requiring implantation of permanent pacemakers.