Aim: To study the nerve supply to the extensor carpi radialis brevis muscle. Materials and Methods: 100 upper limbs of 50 donated embalmed cadavers (45 males & 5 females) of age group ranging from 70 to 80 years were studied in the department of Anatomy at K. J. Somaiya Medical College, Sion, Mumbai, INDIA, the nerve supply to Extensor carpi radialis brevis muscle was observed. The finding was noted after thorough and meticulous dissection of the upper limbs of both sides. The arterial pattern of upper limb were also observed. The photographs of the variations were taken for proper documentation. Results: In 36 specimens of the upper limbs, the nerve supply to extensor carpi radialis brevis was from the deep branch of radial nerve i.e. the posterior interosseous nerve. In the remaining 64 upper limbs, the nerve supply to extensor carpi radialis brevis was from the angle of bifurcation of radial nerve in 22 specimens and from the superficial branch of radial nerve i.e. the radial nerve proper in 42 specimens. Conclusions: The awareness of the nerve supply to extensor carpi radialis brevis from superficial branch of radial nerve is clinically important for surgeons dealing with entrapment or compressive neuropathies, orthopaedicians operating on the fractures of the lower end of the humerus, anaesthetist performing pain management therapies on the upper limb and physiotherapist doing electromyography for evaluating and recording the electrical activity produced by skeletal muscles. A lack of knowledge of such type of variations might complicate surgical repair.