We investigated whether the results of routine urine drug screening for cocaine would be positive after dacryocystorhinostomy. Postoperative urine specimens were analyzed for the presence of benzoylecgonine, the major metabolite of cocaine, by gas chromatography-mass spectrometry. The results of urine tests of all 12 patients were positive for cocaine 24 hours postoperatively. Nine (75%) were positive 48 hours postoperatively, and three (33%) had detectable levels 72 hours after surgery. Patients given cocaine at the time of lacrimal surgery should be warned that they may test positive for cocaine for at least three days postoperatively.