Previously published methods of venous puncture in guinea pigs did not provide reliable venous access for more than a few minutes, and therefore surgical intervention was necessary to cannulate the femoral or external jugular vein or the vena cava. In the present report cannulation of the Vena saphena lateralis via the Vena plantaris lateralis or of the Vena saphena medialis is described by inserting a 22 gauge teflon catheter. These catheters are commercial products. The method is timesaving and inexpensive. Successful cannulation was accomplished in 34 of 35 guinea pigs. No lethal incidents occurred.