Routine preoperative coagulation screening in patients undergoing tonsillectomy and/or adenoidectomy (T and A) is considered by some to be mandatory. T and A is often the first hemostatic challenge in children; therefore, screening is thought to be useful in predicting patients who may experience postoperative hemorrhage. On the other hand, in today's cost-conscious medical environment, routine screening is considered by some to be an unnecessary added expense. At our institution, among 4373 patients who underwent T and A between 1989 and 1994, 43 returned with postoperative bleeding (0.98%). We retrospectively evaluated the usefulness of prothrombin time (PT) and activated partial thromboplastin time (PTT) in predicting intraoperative and postoperative bleeding. All children had extensive bleeding histories taken; however, preoperative laboratory screening was left to the discretion of the attending physician. Preoperative PT/PTT did not predict intraoperative or postoperative bleeding. In our experience, laboratory screening has a very low positive predictive value in detecting occult bleeding disorders or perioperative hemorrhage; thus, we feel it should be used selectively. Routine preoperative PT/PTT is not recommended to screen T and A patients and does not appear to be cost-effective. (C) 1997 Elsevier Science Ireland Ltd.