Background: Although an ambulatory surgical practice continues to increase, there is a few data exist about patient discharge criteria. This study was undertaken to evaluate the usefulness and safety of Aldrete PAR (postanesthetic recovery) score and modified PADSS (modified postaneathesia discharge scoring system) on ambulatory surgery patients for recovery in Korea. Methods: Demographic, anesthetic data, Aldrete PAR score and modified PADSS on 279 patients were recorded. The time to dicharge, from recovery room and postoperative complications were evaluated, also. Results: PAR score and modified PADSS are correlated to length of stay in ambulatory surgery center. 24hr after discharge, 16% patients complained postoperative complications. Pain was most frequent postoperative complication. The PAR score was correlated with the occurrence of the complication. Conclusion: PAR score and modified PADSS are useful scoring systems to evaluate patients and make a decision to discharge the patients from ambulatory surgery center in safe.