Background/Purpose: Controversy persists in the management of perforated appendicitis with regard to antibiotic choice and duration, operative timing, drain utilization, and wound closure, For 2 decades at the authors' institution, patients were treated with ampicillin, gentamicin, and clindamycin for 10 inpatient days, with drains in the abdomen, resulting in lower complication rates than most other published series, Managed care pressures have led to less aggressive medical management regimens with length of stay and financial factors viewed as principal outcome measures with little emphasis on clinical outcomes. In addition, there are little prospective data on clinical outcomes. The authors sought to determine whether our previously documented excellent quality outcomes could be maintained when modifications aimed at decreasing cost and length of stay in our protocol were instituted. Methods: The authors monitored prospectively clinical outcomes in patients with perforated appendicitis treated according to their clinical practice guidelines over a 43-month period. Patients received a single antibiotic, piperacillin-tazobactam, intravenously for 10 days. They were permitted to go home with a percutaneous intravenous catheter for the final 5 days if medical and social criteria were met. Other practices from our earlier protocol were continued, including immediate operation, placement of Penrose drains, and primary wound closure. Results: Of 150 patients treated on our protocol, major complications included intraabdominal abscess in 5 (3.3%), cecal fistula in 2 (1.3%), phlegmon in 3 (2.0%), wound infection in 4 (2.7%), and no small bowel obstructions requiring operation. None of these complications, nor their aggregate, were significantly more common than those reported in 373 patients treated over 11 years on the authors' prior protocol (chi(2), P > .05). Conclusions: Prospective outcome analysis of our protocol shows that a single broad-spectrum antibiotic (allowing portions of therapy to be delivered less expensively on an outpatient basis) effectively can treat postoperative appendicitis with very few infectious complications. These outcome data provide baseline against which future protocols can be compared. All treatment modifications aimed at decreasing costs must be analyzed to ensure quality of care is not unduly compromised. Copyright (C) 2000 by W.B. Saunders Company.