Rupture of the triceps tendon is an uncommon injury-probably the rarest of all tendinous ruptures. Rupture of this tendon associated with radial head fracture was even more rarely reported. Herein, we report a 42-year-old female who had radial head fracture with an undiagnosed triceps tendon rupture following a fall. The diagnosis had been delayed for one month due to local swelling and initial non-visualization of osseous flake of the triceps tendon. Due to the lack of awareness, delay in diagnosis is commonly seen. The reconstruction procedure is frequently needed and the recovering period is prolonged. The history, clinical presentation, causes, prevention of delay in diagnosis, and methods of repair are discussed.