A cost comparison of searching the Iowa Drug Information Service index manually and by computer is presented. Identical searches were performed on a computer system and by hand. The searches were timed and the results compared. Costs of start-up, maintenance, and operation were calculated for the manual and computer systems. Both systems yielded a similar number of relevant references. Start-up and maintenance costs were found more expensive for the computer system, but operational costs were less expensive (p less than 0.05). Operational costs varied according to the number of uses per year. Operational costs were found to increase faster for the manual system than the computer system. At 980 uses per year, the overall cost of the computer system was less than the manual system. A dedicated microcomputer system to search the Iowa Drug Information Service index was found less costly than, and as effective as, the common manual system.