Aim: To study the extensor carpi radialis longus muscle in 100 cadavers. Materials and Methods: This study on extensor carpi radialis longus was performed on 100 (200 specimens of superior extremities) embalmed donated cadavers (90 males & 10 females) in the department of Anatomy of K.J.Somaiya Medical College, Sion, Mumbai, India. Observations: Out of 200 specimens the variation was observed in 22 specimens. The extensor carpi radialis brevis was absent and the extensor carpi radialis longus was giving two tendons in the second compartment of extensor retinaculum before its insertion while passing deep to the abductor pollicis longus. The one tendon of extensor carpi radialis longus inserted into the radial side of the dorsal surface of the base of the second metacarpal bone while the other tendon inserted into the lateral dorsal surface of the base of the third metacarpal bone, with a few fibres inserting into the medial dorsal surface of the second metacarpal bone. The variant extensor carpi radialis longus was supplied by the radial nerve. The finding was noted after thorough and meticulous dissection of the upper limbs of both sides. The arterial patterns of upper limb were also observed. The variation was unilateral. The left upper limb was normal. The photographs of the variations were taken for proper documentation. Conclusions: The variant extensor carpi radialis longus muscle 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.