A case-control study was performed to compare the durability and cost of implanted reservoir catheter systems with percutaneous central venous catheters. Twenty cancer patients had reservoir systems placed in 1985 for chemotherapy delivery. The control group consisted of 60 cancer patients, matched according to age, sex, and diagnosis who were part of a group of more than 700 patients with percutaneous catheters inserted during the same period. The reservoir catheters were found to function for a significantly (P less than 0.0001) longer time (495 +/- 54 days) compared to the percutaneous catheters (197 +/- 22 days). The total cost for each system was calculated by adding the charges for an average insertion (reservoir = $1738, percutaneous = $562) to the maintenance charges accumulated over the catheters' lifespan. Reservoir catheters were associated with a significantly greater total cost than percutaneous catheters ($2233 +/- 54, $1453 +/- 102, respectively) but, if the total cost was spread out over the lifespan of the catheter by dividing the total cost by duration of use, reservoir catheters can be less expensive on a per diem basis. The break point occurs at approximately 6 months. For use less than 6 months, percutaneous catheters are cheaper primarily because of their lower insertion costs, but, for longer periods, reservoir catheters become cheaper because of lower maintenance costs and because a second percutaneous catheterization would likely be necessary.