Although international clinical guidelines generally recommend bacterial stool cultures for patients with acute diarrhea, stool cultures are frequently being requested by physicians regardless of the likelihood of a bacterial infection. This study was conducted to improve the practice of requesting stool cultures by analyzing patterns for stool culture requests by physicians. We retrospectively reviewed 235 stool cultures of patients who visited Gyeongsang National University Hospital from January to February 2017. We analyzed the period of time after which the stool culture was requested after admission, stool characteristics, wet smear, and concomitant tests performed. 38.7% of stool culture requests were made within 3 days of admission. Stool form analysis showed that 36.6% of stools were watery and loose, and 18.8% were firm. Furthermore, >20 leukocytes per high-power field were found only in 0.4% of the wet smears. Among the stool culture requests, 78.7% were prescribed Clostridium difficile culture or toxin tests at the same time. In addition, 13.6% were prescribed diarrhea-causing viral tests as well. Only stool cultures were requested in 10.2% of the cases. Physicians rarely ensure that the adequate criteria are met when requesting for stool cultures. It is necessary to decrease unnecessary diagnostic practices to maintain the quality of care by establishing reliable rejection criteria and the physicians have valid reasons for requesting stool cultures.