Preoperative exams have as objective to reduce the morbidity and peri-operative mortality. In this paper we verified the prevalence of altered laboratorial exams in a population submitted to otolaryngologic surgery. We analyzed 60 patients who accomplished preoperative evaluation at the Department of General Clinic of Clinics Hospital of University of São Paulo with surgeries from July 1997 to January 2000. From 60 ECG performed, we found abnormalities in 12 (20%) cases and from 38 RX, 9 (23,68%) had alterations. Altered laboratorial exams ranged from 1,79% (platelets count) to 30,23% (hematocrit). We observed great percentages of altered laboratorial exams, however, they did not interfere in the patients\' management.