Work-related slip, trip, and fall (STF) incidents can frequently result in serious disabling injuries that impact an employee’s ability to do his or her job. Risk assessments of STF problems for health workers in the operation room (OR) were performed in this study. The following hazards for STF incidents in the OR were found: contaminants on the floor, surface irregularities, loose cords and medical tubing, and improper arrangement of medical equipment and step-stools. The restriction of surgeon and scrubbing nurse movement resulting from the operating gowns worn was a major risk for STF incidents. Recently, the amount of cords, cables, and medical equipment required in the OR for endoscopic and computeraided surgery and computerized physician order entry systems has increased. These circumstances increase the risk of STF incidents in the OR. As countermeasures against these problems, it is essential for the human-machine interface in the OR to be further improved by accounting for OR staff’s workflow. Fatigue management of OR staff should also be further discussed and improved.