The condition known as delta phalanx (or longitudinally bracketed epiphysis) is a rare congenital anomaly first described in 1964. The deformity consists of a triangular bone with an epiphysis running along the shortened side of the phalanx in a proximal to distal direction, making longitudinal growth of the digit impossible. Isolated hallux varus congenitus due to a delta phalanx of the proximal phalanges of both great toes is extremely rare: there have been only three such cases reported, two of which were in one family--the only report of a familial occurrence of this deformity. This present report details the occurrence of isolated bilateral hallux varus congenitus in four members of one family, a father and his three eldest children. All three children show bilateral delta phalanx of the proximal phalanges of both great toes. There are associated thumb nail anomalies, but no suggestion of polydactylism.