Aim to study the variant brachialis muscle. 100 upper limbs of 50 donated embalmed cadavers (45 males & 5 females) of age group ranging from 70 to 80 years were dissected in the department of Anatomy at K. J. Somaiya Medical College, Sion, Mumbai, India. The variant brachialis muscle was observed in 10 specimen. All the upper limbs were thoroughly and meticulously dissected to note the variation of the brachialis muscle. The arterial pattern in the arm was also observed. The photographs of the variation of the brachialis muscle were taken for proper documentation. We found a variation in the insertion pattern of brachialis and entrapped median nerve and brachial artery due to the superficial position of the muscle, in relation to the neurovascular bundle. The brachialis was found to have an additional thick slip from the distal third of the muscle. The accessory slip partly merged with the origin of superficial flexors of the forearm and partly inserted to the medial aspect of olecranon process. The median nerve and brachial artery passed under this additional slip of brachialis. Knowledge of variation in the pattern of muscle insertion and possible neurovascular entrapment is important for orthopedic surgeons, plastic surgeons and physiotherapists. The abnormality reported here might result in neurovascular compression symptoms in upper limb and some mechanical advantages or disadvantage in the flexion of elbow joint.