Aim to study the accessory flexor carpi ulnaris 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 accessory slip of flexor carpi ulnaris muscle was observed in 2 specimens. The neurovascular pattern was also observed. The photographs of the variation of the flexor carpi ulnaris muscle were taken for proper documentation. The accessory slip of flexor carpi ulnaris muscle was observed in 2 specimens. The accessory slip of flexor carpi ulnaris originated from lower part of it’s tendon and got inserted into the palmar aponeurosis and the tendon of palmaris longus muscle. The total length of flexor carpi ulnaris muscle is 26 cm, with a muscular belly of 22 cm and 3.5 cm of width and 0.5 cm of thickness. The total length of an accessory slip of flexor carpi ulnaris muscle is 3 cm, and thickness 0.5 cm. The accessory muscle is located between the tendon of flexor carpi ulnaris muscle and palmaris longus muscle. The knowledge of such accessory slip of flexor carpi ulnaris muscle may be clinically important for plastic surgeons doing flap surgeries and for the surgeon dealing with cubital tunnel syndrome.