The syndrome of spondylolisthesis and tight hamstrings occurs in adolescent children and is characterized by severe restriction of straight-leg raising, inability to bend the trunk forward, and a peculiar gait. The mechanism that produces the hamstring spasm is not well understood, but certainly hamstring tightness may accompany any irritative lesion of the cauda equina. We have presented detailed reports of two cases of spondylolisthesis and tight hamstrings, which we ourselves treated surgically, and we have knowledge of seven similar cases supplied by five of our colleagues.