A bar-code stock ordering system installed in the ambulatory-care pharmacy and sterile products area of a hospital pharmacy was compared with a manual paper system to quantify overall time demands and determine the error rate associated with each system. The bar-code system was implemented in the ambulatory-care pharmacy in November 1987 and in the sterile products area in January 1988. It consists of a Trakker 9440 transaction manager with a digital scanner; labels are printed with a dot matrix printer. Electronic scanning of bar-code labels and entry of the amount required using the key-pad on the transaction manager replaced use of a preprinted form for ordering items. With the bar-code system, ordering information is transferred electronically via cable to the pharmacy inventory computer; with the manual system, this information was input by a stockroom technician. To compare the systems, the work of technicians in the ambulatory-care pharmacy and sterile products area was evaluated before and after implementation of the bar-code system. The time requirements for information gathering and data transfer were recorded by direct observation; the prevalence of errors under each system was determined by comparing unprocessed ordering information with the corresponding computer-generated "pick lists" (itemized lists including the amount of each product ordered). Time consumed in extra trips to the stockroom to replace out-of-stock items was self-reported. Significantly less time was required to order stock and transfer data to the pharmacy inventory computer with the bar-code system than with the manual system.(ABSTRACT TRUNCATED AT 250 WORDS)