The results of a comparative double-blind clinical trial involving peripheral intra-arterial DSA performed with low iodine iopamidol concentrations (150 and 200 mg. I/ml.) are reported. Forty-six patients were examined for vital signs, local (heat and pain sensations) and systemic reactions and monitored throughout the procedure. No untoward effect was observed apart from mild local reactions, which on the other hand did not produce any movement artifacts. Image quality was good to optimal in 98% of the cases. In no case were higher concentrations of contrast medium (cm) needed. No significant differences between the two concentrations of cm used were observed with respect to either contrast ability or tolerability.