This randomized controlled experimental study was conducted in the endoscopy unit of a private hospital between March and June 2023 to evaluate the effect of nurse-delivered counseling on pain, anxiety, and comfort levels in patients undergoing colonoscopy. Sixty patients were assigned to intervention (n=30) and control (n=30) groups. The intervention group received counseling beginning 24 hours before the procedure, including face-to-face education, telephone support, and reminder messages, while the control group received routine care. Anxiety was assessed using the State Anxiety Scale, and pain and comfort were evaluated using the Visual Analog Scale.