Long-term venous access for leukapheresis, repeated blood sampling, and administration of drugs and fluids can be accomplished nonsurgically in Yucatan miniature swine. The catheter is placed under fluoroscopic guidance into the inferior vena cava using a needle and guidewire. This procedure has the advantage that it avoids a surgical incision, allows high flow rates, exists conveniently on the lower back, and can be replaced easily in the event of mechanical failure or thrombosis. Actuarial analysis of the duration of patency disclosed that of 41 catheters placed in 30 animals, the probability of function at 28, 42, and 54 days was 75%, 50%, and 25%, respectively. Eleven nonfunctioning catheters were replaced and nine of these continued to function until the completion of the experiment. No catheters were removed due to infection. Chronic catheterization of the inferior vena cava is a convenient method for long-term venous access in swine.