Seven first degree relatives in three generations of a family with partial sacral agenesis are reported. Anterior sacral meningoceles were found in five cases, four of whom had severe constipation, one with urinary voiding dysfunction, and another without constipation who had low pressure headaches and dyspareunia. The anomalad was transmitted in an autosomal dominant fashion with incomplete penetrance and variable expression. This entity should be considered in all children and adults with severe constipation from birth, a family history of constipation and/or where constipation is refractory to medical therapy.