BACKGROUND The purpose of this study was to explore the feasibility of ulnar groove plasty guided by a three-dimensional (3D) printing technique for treatment of moderate to severe cubital tunnel syndrome (CuTS) caused by elbow osteoarthritis. MATERIAL AND METHODS Patients with moderate to severe CuTS secondary to osteoarthritis of the elbow were enrolled in our hospital from April 2015 to March 2018. Based on a previously proposed "elbow canal index", a 1: 1 model of the elbow joint was printed using CT image data collected preoperatively. After computer-aided measurement, the standard for enlargement of the ulnar nerve groove was calculated and a personalized "trial model" was created by 3D reconstruction. After intraoperative exposure of the ulnar nerve sulcus, the proliferative osteoid was burred with a grinding drill, and the cubital enlargement was verified by the trial model. The ulnar nerve was decompressed and reincorporated into the enlarged cubital canal, and the Osborne ligament was zig-zag elongated and reconstructed. RESULTS None of the patients reported experiencing medial elbow instability, medial elbow pain, ulnar nerve subluxation, flexor-pronator weakness, or incision infection. There was significant improvement of the motor nerve conduction velocity, sensory nerve conduction velocity, two-point discrimination of the little finger, grip strength, pinch strength of the thumb and index finger, VAS score, and DASH score in this study (P<0.001). CONCLUSIONS Ulnar groove plasty guided by a 3D printing technique may be another effective treatment of moderate to severe CuTS caused by elbow osteoarthritis.