Aim: Coronary angiography involves the selective injection of a radiographic contrast agent in the coronary arteries. Intravenous heparin may be given at the time of catheter insertion in some center. But optimal strategy for administering heparin to patients undergoing coronary angiography remains unclear. The aim of this study is evaluation of heparin administration effects during diagnostic coronary angiography in Ekbatan hospital centre. Materials and Methods: This was a randomized controlled clinical trial study which was done on 500 patients, undergoing diagnostic coronary angiography via femoral approach. Patients initially were divided to two groups, 250 cases were on intravenous (heparin) and 250 on no heparin. We studied during and post angiographic vascular complications (active bleeding, groin hematoma, retroperitoneal hematoma, pseudoaneurysm, Ischemic cerebral and peripheral vascular accident and clot during angiography). The data such as age ,sex, ejection fraction, positive history of hypertension, diabetes mellitus, severe peripheral vascular disease, aortic stenosis and coagulopathy were collected via questionnaires. All patients with CAD referred to Ekbatan hospital for coronary angiography. Patients with severe AS, PVD , coagulopathy and angiography procedures more than 30 minutes were excluded.