Even though preoperative marking of the stoma area is considered important for the prevention of postoperative complications, not all healthcare institutions have universally adopted this practice. A multicenter, retrospective, descriptive study was conducted to determine the effect of stoma site marking on stomal and peristomal complications. The 1-year study included 748 patients (408 [54.5%] male, mean age 56.60 +/- 16.73 years) from eight stomatherapy units in Turkey. history of preoperative stoma site marking, person per-Patient data, including age, gender, diagnosis, type of surgery, forming the marking, and postoperative complications, were obtained from patient records, abstracted, and analyzed. Cancer was the reason for the operation in 545 (72.9%) of the cases. In 287 patients (38.4%), the stoma and wound care nurse and/or surgeon marked the stoma area; this occurred 1 day before or on the day of surgery according to Wound Ostomy Continence Nurses Society and American Society of Colon and Rectal Surgeons recommendations. Stomal/peristomal complications developed in 248 (33.2%) persons; the most frequently observed complications in patients were parastomal skin problems (136, 48.7%), mucocutaneous separation (52, 18.6%), and retraction (31, 11.1%). The rate of complications was higher among patients whose stoma site was not marked than among those whose stoma site was marked (22.9% and 46%, respectively; P < 0.001). The results of this study confirm the stoma area should be marked preoperatively in all planned surgical interventions in order to reduce the risk of postoperative complications. Additional prospective and experimental studies on effectiveness of preoperative stoma site marking should be conducted with larger sample groups.