A family with hereditary hollow visceral myopathy is described, with characteristic variation in expression between affected members. Very severe and widespread involvement of the gastrointestinal and urinary tracts in 1 patient contrasted with isolated urinary tract involvement in 2 others, and it is suggested that hollow visceral myopathy should be considered in the differential diagnosis of primary detrusor failure. The management of urinary tract involvement is discussed and a conservative approach is recommended.