We report a case of isolated rupture of the separate insertion of the short head of biceps on the radial tuberosity. This case occurred in a 52-year-old male fitness instructor who lifted a heavy weight. The patient presented with pain, bruising of the anterior elbow and weakness of elbow flexion. There was no bunching of the distal biceps and the hook test was normal. The rupture and location of the tendon ends was identified by several transverse and longitudinal ultrasound images and then definitively confirmed by magnetic resonance imaging. The rupture was surgically repaired, resulting in good functional ability. Early detection is vitally important for optimal management, especially when functional disability is present.