1. Thirteen cases of congenital pseudarthrosis of the clavicle conforming to the classical picture are presented, together with five cases of pseudarthrosis occurring for various other reasons, and nine cases of congenital pseudarthrosis that form a special group because there was a strong family history.

2. Treatment, if desired by the patient, is easy, but should be deferred until the age of four or five years.

3. The etiology remains obscure. Our embryological study does not support the theory that the clavicle normally develops from two ossification centres that may fail to coalesce. Although in thirteen of our patients there was no family history of pseudarthrosis, there was another group of nine patients who presented a strong family history, and it seems certain that in some instances congenital pseudarthrosis of the clavicle can be transmitted genetically.

1. Eighty-two patients out of 114 with arthrogryposis seen at the Hospital for Sick Children, Toronto, during the period of 1950-65 have been studied, and the literature has been reviewed.

2. Arthrogryposis is considered to be caused by a failure of normal development.

3. Respiratory infection in the first five years is the major hazard to life. If these children survive the first five years, the expectation is that they will reach maturity and find a place in the community.

4. Children with upper limb involvement develop remarkably good function which can be improved by carefully planned operations.

5. Operation has a much larger place in the treatment of affected lower limbs.

6. Three out of four children with lower limb involvement can be enabled to walk if tile need for repeated operation is accepted.

7. Excision of the talus is a useful operation in the management of club foot ill arthrogryposis.

8. Early treatment is more effective than late ill controlling deformity and improving function.