Various serum enzyme activities were studied in 15 adult patients before aortography and at the 6th hour and on the first five days after investigation; and at comparable intervals in 8 adult patients who had a bilateral transfemoral arteriography. A significant rise in serum creatine phosphokinase (CPK) level was noted at the 6th hour (p < 0.01), on the 1st day (p < 0.001) and on the 2nd day (p < 0.05) after aortography. Serum aspartate-aminotransferase (ASAT) level increased significantly (p < 0.02) on the 1st day after aortography. No significant change occurred for those two enzymes after transfemoral arteriography. In both groups minor changes were noted for the other enzymes studied: lactic dehydrogenase (LDH), alanineaminotransferase (ALAT) and gamma glutamyl transpeptidase (gamma GT). Rise in CPK and ASAT levels after translumbar aortography is attributable to skeletal muscle trauma and to the retroperitoneal haematoma at the site of puncture. Agents used in anesthesia are apparently not responsible.