Intra-arterial digital subtraction angiography was performed in 25 patients, using Iopamidol in three different iodine concentrations: 50, 75, and 100 mg I/ml and comparing the results obtained with each concentration. The following vessels were explored: the aortic arch, the common carotid artery, the internal and external carotid arteries and the vertebral artery. The contrastographic effect was satisfactory when lower iodine concentrations were used in very selective catheterizations while greater concentrations of iodine were needed in less selective procedures.