background: Although the transradial approach has reduced vascular complications, radial artery occlusion is still considered one of its limitations. The aim of this study was to evaluate radial artery patency after transradial cardiac catheterization. Methods: Prospective cohort study of patients undergoing cardiac catheterization using the transradial approach. Procedures were performed with 5 F and 6 F catheters with the administration of 5,000 IU of heparin and 200 μg of nitroglycerin through the radial sheath. Radial artery blood flow was assessed by Doppler before, immediately after bandage removal and 7 days after the procedure. Results: The study included 120 patients of which 42.5% were males, with 59.1 ± 10.6 years of age, 25.8% were diabetic, weighing 77.4 ± 14.2 kg and height of 166 ± 8.1 cm. The number of catheters used was 2.3 ± 0.5 per patient, 55.8% using 6 F sheaths. The duration of the procedure was 14.8 ± 5.2 minutes, the puncture time was 129.7 ± 124.1 seconds, and the fluoroscopy time was 4 ± 2.3 minutes. Radial spasm and crossover to the femoral technique occurred in 20.8% and 1.7% of the procedures, respectively. Significant hematoma was observed in 2.4% of the patients. At 1 week of followup, arterial occlusion was observed in 1.7%, and reduced blood flow in 26.7% of the patients. Conclusions: Radial artery occlusion following diagnostic procedure using the