Iodixanol is a new nonionic, dimeric contrast medium. With the addition of 18 mmol/l Na+ and 0.3 mmol/l Ca++ to iodixanol 320 mg I/ml a plasma-isotonic solution was obtained. The purpose was to evaluate the suitability of iodixanol for use in cardioangiography by determining the diagnostic efficacy, patient tolerability, and cardiac and renal side-effects. Initially, 14 patients with coronary artery disease were examined using iodixanol. A double-blind, randomized study was then performed in 72 patients, comparing iodixanol and iohexol. Serum and urine were sampled before the examination, and one and 2 days after. The diagnostic information was good and the number of adverse events low with iodixanol. The patients reported significantly less of a sensation of warmth following injection of iodixanol than iohexol. Our results also indicate that iodixanol 320 mg I/ml influences renal function to a lesser degree than does iohexol 350 mg I/ml. We therefore conclude that isotonic iodixanol is a safe contrast medium for use in cardioangiography.