Two male siblings born to consanguineous parents, with the diagnosis of congenital insensitivity to pain with anhydrosis are evaluated. The patients presented with unexplained bouts of fever, self-mutilation, repeated trauma and inability to sweat. Physical examination revealed both siblings to be insensitive to pain and temperature. The electron microscopic study of the skin was unremarkable whereas sural nerve biopsies yielded an essential lack of unmyelinated fibers.