The natural history of 120 popliteal cysts in children has been reviewed. Of seventy untreated cysts fifty-one disappeared spontaneously during a mean period of one year and eight months. Of fifty cysts submitted to operation, twenty-one recurred in a mean period of seven months. Three children with recurrences had more than one further operation. Most popliteal cysts in children disappear spontaneously, and operation without very good reason is unjustified.

1. Trigger thumbs present at birth can be safely watched for twelve months because there is an expected spontaneous recovery rate of at least 30 per cent.

2. Trigger thumbs in children first noticed between the age of six to thirty months can be safely watched for six months because there is an expected spontaneous recovery rate of about 12 per cent.

3. Delayed operation left no residual contracture of the interphalangeal joint provided the release was done before the age of four years.

4. Operation is recommended if the child is over the age of three years when first seen.