Small forearm is a rare congenital malformation, also known as ulnar club hand, and less common than radial club hand. The onset is mostly unilateral, with the right side being the most common, and there are more males than females. The diagnosis is not difficult based on the clinical manifestations, concomitant deformities and radiographic features. The thumb and index finger are present in this child with good mobility, but the ulnar column is absent. The affected forearm is small, short and tilted to the ulnar side, and the radial head is dislocated, limiting the rotation of the forearm, but the function of the wrist and elbow joints is not impaired. Patients may also have carpal bone defects, commonly the pea bone, the hook bone, most of the angular bone and the cephalic bone, and sometimes the 4th and 5th metacarpal bones are also absent. The radius is bowed outward and becomes more pronounced as the child grows. About 20% of children have syndactyly, and other deformities of the body include fibular agenesis, clubfoot and spina bifida. Most of the cases are unilateral, with the right side being the most common. The thumb and index finger are present with good mobility, but the ulnar column is absent. The affected forearm is small, short and tilted to the ulnar side, and the radial head is dislocated, limiting the rotation of the forearm, but the function of the wrist and elbow joints is not impaired. Patients may also have carpal bone defects, commonly the pea bone, the hook bone, most of the angular bone and the cephalic bone, and sometimes the 4th and 5th metacarpal bones are also absent. The radius is bowed outward and becomes more pronounced as the child grows. About a few children have syndactyly, and other associated deformities include fibular agenesis, clubfoot, and spina bifida.