A systematic dissection of both feet of a six-week-old infant with congenital convex pes valgus has been reported. The findings of the dissection follow:

1. There was abnormal tightness in the following muscle-tendon units:anterior tibial, extensor hallucis longus, extensor digitorum longus, and peroneus brevis. The muscles were grossly and histologically normal. The problem was assumed to be one of length deficit of the muscle-tendon units.

2. The posterior tibial tendon and both peroneal tendons were anteriorly displaced and lying in grooves on the medial and lateral malleolus respectively.

3. The vertical position of the talus is in reality an equinus position, resulting from its intimate capsular attachments to the calcaneus, which is directed plantarward by the tight Achilles tendon.

4. The head of the talus was oval rather than spherical. We believe this is an adaptive change due to the abnormal talonavicular relationship.

5. Only two of the three normally present articulating facets on thc superior surface of the calcaneus were present, and these were abnormal.

6. The long asis of the calcaneus is directed laterally to the normally directed long axis of the talus.

7. Since bone and joint changes are minimum in the infant, it is logical to assume that such changes when found in late cases are the result of persistent soft-tissue abnormalities.

Since the term congenital vertical talus focuses attention upon one small aspect of this condition, we believe that its use should be discouraged.