The hospital, pharmacy, and antibiotic costs for patients with penetrating abdominal trauma were compared with reimbursement received; these costs were also analyzed to assess the potential impact of a total prospective pricing system (PPS). During a four-year period, 46 patients admitted solely for penetrating abdominal trauma were retrospectively evaluated: their discharge summaries indicated that, for 9 patients, reimbursement was based on diagnosis-related groups (DRGs) under the PPS; 9 patients had private insurance; and 28 were classified as "self-paying/no insurance." All costs, corrected for inflation, were reported in 1989 dollars. Antibiotics represented 22.5%, 1.7%, and 0.5% of pharmacy, hospital, and DRG reimbursement, respectively; pharmacy costs were 8.5% of hospital costs and 2.3% of DRG reimbursement. For all 46 patients, a net loss of $295 per patient was incurred. Four patients accounted for 43% of the hospital costs. If the hospital had been reimbursed for all of these patients by prospective pricing and DRGs, it would have had a median profit of $9730 in 42 of 46 patients. Costs exceeded DRG reimbursement in the remaining four patients by a median of $8210. Antibiotic costs and pharmacy costs represent a small portion of hospital costs and DRG reimbursement for patients with penetrating abdominal trauma; thus, cost containment efforts in these patients should be directed at other ancillary services and length of stay.