In 231 adults the frequency and the pattern of the retroaortic left renal vein were studied. We observed a retroaortic left renal vein in 9.09% ("renal collar" in 5.62%, single retroaortic left renal vein in 3.46%. According to our results and to the findings in the literature a retroaortic left renal vein can be expected in 13.67% ("renal collar" in 9.53%, single retroaortic left renal vein in 4.13%).