Introduction: Several studies suggest that the primary success of percutaneous coronary intervention (PCI) is less in diabetic patients than others and that complications and restenosis are more frequent. This was therefore assessed in icelandic diabetic patients. Methods: From 1987 to 2002 a total of 4435 PCI s were performed and of these 377 (8.5%) were in diabetic patients. The clinical background of the patients, primary success after PCI, and in-hospital complications, were retrospectively assessed. Results: The relative frequency of diabetics undergoing PCI increased significantly during the study period from 5.7% to 10.6% (p=0.001). In diabetic compared with non-diabetic patients, the mean age was higher (64 +/- 10 versus 62 +/- 10 years; p=0.002), and women were more frequent. Hypertension and hypercholesterolaemia were more common in the diabetics and a larger proportion of them were current smokers. Further more, diabetics more frequently had a previous history of myocardial infarction, coronary artery bypass surgery, PCI, unstable angina and triple-vessel disease. The overall use of stents was similar in the groups, as was PCI for clinical restenosis (13.3% versus 10.8%; p=0.15). The primary success rate was comparable in diabetics and non-diabetics (93% versus 92%). The need for acute coronary bypass post-PCI was similar in the groups, whereas diabetics more rarely had a three fold increase in creatinine kinase-MB values. Overall, in-hospital mortality was low (0.4%), but higher in diabetic than non-diabetic patients (1.1% versus 0.3%; p=0.04). By multivariate analysis, significant independent predictors of in-hospital mortality were: Primary PCI for acute ST-elevation infarction, number of stenotic coronary vessels, diabetes and age, while the presence of hypercholesterolemia was an inverse predictor. Conclusion: The primary success rate for PCI is comparable in icelandic diabetic and non-diabetic patients. Although few patients died in hospital after PCI, the diabetic patients did have a higher in-hospital mortality rate.