Objectives: We investigated the relationship between coronary risk factors (age, gender, smoking, diabetes mellitus, hypertension, family history, and hypercholesterolemia) and the development of restenosis after percutaneous transluminal coronary interventions. Patients and Methods: A total of 162 patients underwent successful percutaneous transluminal coronary angioplasty with or without stenting. Follow-up coronary angiograms were performed in 107 patients (15 females, 92 males; mean age 55.5 years, range 39 to 77 years) after a mean of 184 days. Logistic regression was used for the analysis of the associations between the variables and restenosis. Results: Restenosis was detected in 47 patients (39%). Age, gender, smoking, hypertension, hypercholesterolemia, family history, a history of previous myocardial infarction, ejection fraction, and the degree and location of stenosis were not found as significant variables in the development of restenosis. However, restenosis was significantly correlated with diabetes mellitus (-2 log likelihood 28.28, p=0.0002). The rate of restenosis was significantly lower in the stent group (n=56, 52%) (p<0.01). Conclusion: Diabetes mellitus presents as the most significant risk factor in the development of restenosis after coronary angioplasty and stenting.