Cavanagh syndrome is a rare, isolated congenital thenar hypoplasia with characteristic clinical, radiological and electrophysiological features. It has never been reported to occur in association with absent radial artery. We report the case of a boy with left sided congenital thenar hypoplasia fulfilling the characteristic clinical, radiological and electrophysiological features of Cavanagh syndrome, associated with congenital absence of left radial artery. We also discuss the possible underlying aetiopathology of Cavanagh syndrome.