Two hundred and twenty-five patients investigated by left ventricular, coronary artery and/or proximal aortic angiography were randomly assigned to one of three contrast medium groups (Hexabrix 320, Niopam 300 or Omnipaque 300). Subjective response to injection of contrast medium was noted at the time of investigation and during the next 24 h. No significant difference was found between the three currently available low-osmolar contrast media.