The L1 cell adhesion molecule (L1CAM) protein is found primarily in the nervous system and is important in neuronal adhesion, migration, neurite outgrowth, and myelination. It is extremely rare that Hirschsprung's disease (HSCR) merges with a disorder showing abnormality of the L1CAM genes such as acrocallosal syndrome (ACS) or X-linked hydrocephalus (XLH). Herein, we report 2 cases--the first showed abnormality of the L1CAM genes and developed HSCR; and the second, with clinically suspected XLH, was successfully operated on for HSCR. When a patient with ACS or XLH presents with constipation, we must consider HSCR in the differential diagnosis, and early treatment is important. Furthermore, it is desirable to select a line treatment of HSCR to prevent infection of the ventriculoperitoneal shunt if the patient requires it.