Between June 1982 and April 1984, 67 adult granulocyte donors were randomized to receive external arteriovenous shunts or modified right atrial catheters as vascular access for daily granulocyte collections using blood cell separators. Six of 32 donors with shunts and 2 of 35 donors with right atrial catheters experienced failure of the access method. Local infection occurred in one donor with a shunt and one donor with a right atrial catheter. Bacteremia occurred in one donor with a right atrial catheter. Specified whole blood flow rates of 50-65 ml/minute were achieved with 28 of 32 shunts and 29 of 35 right atrial catheters (P = NS). The majority of the donors in each group tolerated the vascular access without significant problems. This study demonstrates that modified right atrial catheters can be successfully used as method of vascular access for single donor granulocyte collection with blood cell separators.