After a celiac plexus block with ethyl alcohol, patients sometimes complain of symptoms of alcohol intoxication. We studied the consecutive changes of arterial and venous blood alcohol concentrations in 11 patients and investigated whether an arteriovenous difference exists. We performed a celiac plexus block with 10 ml absolute ethyl alcohol. The sampling sites were radial artery and internal jugular vein. Blood samples were collected at 0, 5, 10, 15, 30, 60, 120, 240 and 480 minutes after the block. The maximum level was reached 15 minutes after injection in both arterial and venous blood, 29.9 +/- 19.4 and 27.7 +/- 21.8 mg/dl (means +/- SD), respectively. Arteriovenous differences were observed 5 and 10 minutes after ethyl alcohol injection (p less than 0.01). There was a significant negative correlation between the ratio of arteriovenous differences to venous sampling and the time elapsed after the block (r = 0.41, p less than 0.01).