Cardiac catheterisation with 5 French catheters. From the beginning of November 1987 to the end of January 1989, 526 coronary arteriograms and left ventricular angiograms were performed with 5 French coronary catheters. In 448 (85%) patients diagnostic pictures were obtained with three standard types of 5 French catheters (No 4 Judkins): that is, left coronary, right coronary, and pigtail catheters. In 60 patients (11.4%) various other 5 French catheters were required to complete the study. In nine patients (1.7%), a 7 or 8 French catheter was used. Major complications causing cardiac arrest or requiring urgent operation developed in five patients. Sixty two patients (11.77%) had minor complications that required sublingual nitrates or a single bolus of atropine, or developed a haematoma that did not need intervention or had a mild reaction to the contrast material. Complications of moderate severity developed in 17 patients (3.2%): severe chest pain, arrhythmia requiring a temporary pacemaker, contrast reaction associated with hypotension, haematoma requiring blood transfusion, or a transient ischaemic episode. There were no deaths. 5 French catheters were used for routine coronary angiography and left ventriculography in 98.3% of patients. There were no major complications related to femoral artery puncture. The routine use of 5 French coronary catheters should increase the feasibility of safe coronary angiography in outpatients and should reduce the cost of this investigation. 