Heterotopic ossification is an abnormal formation of true bone within extraskeletal soft tissues. The interosseous membrane (IOM) runs obliquely from radius to ulna and attaches to their respective interosseous borders. It is an occasional site for heterotopic ossification (HO) that involves the development of mature lamellar bone. Heterotopic ossification resulting in radio-ulnar cross union occurs in 2% of all forearm injurie Heterotopic ossification resulting in radio-ulnar cross union occurs in 2% of all forearm injuries Heterotopic ossification resulting in radio-ulnar cross union occurs in 2% of all forearm injuries Heterotopic ossification resulting in radio-ulnar cross union occurs in 2% of all forearm injury Heterotopic ossification resulting in radio-ulnar cross union occurs in 2% of all forearm injuries Heterotopic ossification resulting in radio-ulnar cross union occurs in 2% of all forearm injuries the radius, hence to the ulna and humerus. The posterior relations near the carpus are the anterior interosseous artery and the posterior interosseous nerve. Heterotopic ossification resulting in radio-ulnar cross union occurs in 2% of all firearm injuries. During the routine undergraduate demonstration classes in the department of Anatomy at BLDEU’s Shri B. M. Patil Medical College, Bijapur, we found Heterotopic ossification resulting in radio-ulnar cross union occurs in 2 % of all forearm injuries. We report a case of ossification of the interosseous membrane (OIM) in a 17-year-old boy who had a history of trauma 1 month back followed by pain and swelling in the right wrist. The plain radiograph showed OIM in the distal interosseous membrane of the radius and ulna of the right hand. MRI showed bone intensity bridging the distal shaft of the radius and ulna.