The radial arterial approach has been shown to be valuable for coronary angioplasty. The aim of this study was to evaluate the use of the left radial and right femoral approaches for diagnostic coronary angiography. The authors performed a prospective non-randomised series of consecutive diagnostic coronary angiogrammes with small calibre (4 french) catheters by the left radial (100 patients) and right femoral (100 patients) arteries. The feasibility, results and complications were compared. The study showed that diagnostic coronary angiography with 4 F catheters is feasible with a high success rate, both from the left radial (99%) and right femoral (100%) approaches (NS). The duration of the procedure tends to be longer when the radial approach is used (19.2 +/- 1.3 min) than by the femoral artery (16.3 +/- 1.1 min) (p = 0.06). The duration of irradiation is longer with the radial approach (6.7 +/- 1.2 vs 4.9 +/- 0.9 min) (p = 0.0001). Local complications are minor by either approach (N = 5 vs N = 6 patients; p = NS), and there were no major complications. The tolerance of the procedure was not as good when the radial artery was used (N = 5) compared with the femoral artery (N = 1 patient) because of arterial spasm when the catheters were changed. The authors conclude that the left radial and right femoral arteries can be used routinely for diagnostic coronary angiography with small catheters (4 French). The left radial approach allows immediate mobilisation of the patient but the duration of the procedure and the exposure to irradiation are longer.