The objectives were to assess the parenteral route for cimetidine and ranitidine and to determine excess medication costs associated with inappropriate use. Criteria were based on clinical situations that do not permit oral therapy, result in questionable dry absorption, or require a more rapid onset of action. The parenteral route was assessed as appropriate, inappropriate, or questionable. During two months, parenteral therapy was prescribed for 199 adult inpatients. Initially, 63 percent received the parenteral form appropriately; only 16 percent continued to receive the parenteral form appropriately throughout therapy. Less than half of the parenteral doses were determined to be appropriate. A major reason appears to be that orders are not changed as patients' conditions improve. Excess medication costs attributed to inappropriate parenteral therapy for the study period amounted to $6796 or $8002, depending on whether questionable doses were considered appropriate or inappropriate, respectively. An annual projected savings of $40,776 or $48,012 could be achieved if oral doses had been administered in place of inappropriate parenteral therapy.