Aims: To investigate the incidence of ordering tests for tumor markers which are used in cancer diagnosis, follow-up treatment and detection of recurrence, the rate of elevation in benign diseases and which clinics order them frequently. Materials and Method: Data for the tumor markers carbohydrate antigen 19-9 (CA 19-9), carcinoembryonic antigen (CEA), cancer antigen 125 (CA 125), cancer antigen 15-3 (CA 15-3) and alpha-fetoprotein (AFP) that were ordered by all the clinics in our Hospital between 2010 and 2011 were screened. When excluding repeated orders the results of 3,416 patients were available. It has been determined that in which benign diseases were the tumor markers frequently ordered and which of these conditions had high levels of them. Results: CA 19-9 was ordered for 1,858 patients 191 (10.3%) were malignant while 1667 (89.7%) were ordered in benign diseases. For CEA the total was 1,710, 226 (13.2%) malignant and 1484 (86.8%) benign, and for CA 125 1267, 111 (8.8%) malignant and 1156 (91.2%) benign. AFP was ordered for 1687 cases, 80 (4.7%) malignant but 1607 (95.3%) benign. CA 15-3 was ordered 1449 times, 174 (12%) for malignant and 1275 (88%) for benign diseases. In all cases, considerable proportions were positive. Conclusions: It was shown that clinicians frequently order tumor markers for benign conditions. The findings of this study has shown that tumor markers are used widely without indications as cancer screening tests.