Objectives: Iopentol (Nycomed Imaging AS, Oslo, Norway) and iopromide (Schering AG, Berlin, Germany) are low-osmolar, non-ionic, iodinated contrast media (CM) used in abdominal CT examinations. The intravenous safety profile and radiological efficacy of iopentol and iopromide were studied in 518 patients. Specifically, frequency of adverse events (AEs), subjective change in quality of diagnostic information, and quantitative enhancement characteristics were compared. Materials and methods: A prospective, double-blind, randomized, multicentre, parallel-group study was conducted at 8 hospitals. Patients received 100 ml of either iopentol 300 mg I/ml or iopromide 300 mg I/ml. Results: The incidence of patients with AEs was statistically significantly lower in the iopentol group compared to the iopromide group (2.3 % vs. 8.9 %, p < 0.001). Discomfort was frequent in both groups (44.8 % vs. 49.4 %, p = 0.33), sensation of heat and warmth being most common. Overall, diagnostic information was similar in both groups. Both CM gave high percentages of examinations rated as optimal (87.1 % vs. 90.5 %, p = 0.34) and in which diagnostic confidence was increased (87.5 % vs. 91.1 %, p = 0.22). No significant differences between the two CM were found concerning quantitative enhancement characteristics. Conclusions: In this study iopentol was significantly safer than iopromide for contrast enhanced CT examination of the abdomen. Radiological efficacy was similar with both CM.