BACKGROUND: Knowledge about the simultaneous influence of diabetes and hypertension on outcome among patients with ischemic heart disease is limited. The objective of this survey was to describe the characteristics, treatment and outcome among patients with acute coronary syndromes (ACS) in relation to previous history of hypertension (HT), diabetes mellitus (DM) or a combination of the two. METHODS: Consecutive patients admitted to the Coronary Care Unit, Sahlgrenska University Hospital, Goteborg Sweden aged <80 years fulfilling criteria for ACS during 1995 until 2001 were followed for a median of 8 years. RESULTS: A history of HT was found in 974 (42%) of 2329 patients and a history of DM in 446 (19%). Patients with DM or HT were older, more often female and more frequently had previous atherosclerotic manifestations. Patients with DM, irrespective of HT, had a higher prevalence of prior heart failure, as well as higher Killip class and heart rate at admission. Signs of myocardial ischemia on the admission electrocardiogram (ECG) were more prevalent without HT or DM. While HT was weakly associated with impaired long-term prognosis (HR 1.18; 95% CI 1.02-1.37), DM was a strong predictor of death (HR 1.79; 95% CI 1.52-2.10) and the combination was even additive (HR 2.10, 95% CI 1.71-2.57). CONCLUSION: ACS patients with a history of HT and DM had a higher age-adjusted, long-term mortality risk than ACS patients without such a history. DM appeared to be more strongly associated with mortality than HT, but its combination was additive.