Aim: To study the nerve supply to extensor carpi radialis brevis muscle. Materials and methods: 50 upper limbs of adult human cadavers irrespective of sex were studied in the Department of Anatomy at Kempegowda institute of medical sciences, Bengaluru, Karnataka, the nerve supply to extensor carpi radialis brevis (ECRB) muscle was observed. Study was done by dissection method. The following parameters: source of nerve to ECRB, site of division of radial nerve in relation to lateral epicondyle were noted and the distance between origin of nerve to ECRB and point of entry into the muscle was measured. Results: In 29 specimens the nerve supply to extensor carpi radialis brevis was from posterior interosseus nerve (PIN), in 12 specimens from superficial branch of radial nerve and in 9 specimens from the angle of bifurcation of radial nerve and none of the specimens showed innervation from the radial nerve trunk. In 33 specimens, radial nerve divided at the level of lateral epicondyle, in 15 specimens it was above the level of lateral epicondyle and in 12 specimens showed division below the level of lateral epicondyle. Average length of nerve to ECRB on right and left side was found to be 4.4 cm and 4.1 cm respectively. Conclusion: In 24% of specimens the nerve supply to extensor carpi radialis brevis was from the superficial branch of radial nerve, the knowledge of which is clinically important for surgeons and orthopaedicians before undertaking surgical procedures such as free functional muscle transfer, tenotomy etc.