Information on the family history of renal stone disease was obtained from over 2500 middle-aged men in a general health survey. A family history of stones was significantly more common among the stone-formers than amoung the controls, largely due to an increased frequency of stones among the fathers and brothers of the propositi. This study thus supports previous suggestions that genetic factors play a part in the predisposition to stone formation. An increased tendency was also noted, however, among the wives of those whose relatives had stones, which suggests that environmental factors are involved. Subjects with a family history of renal stones did not exhibit any particular characteristics in their laboratory profiles, but they appeared to be more prone to develop early and frequent recurrences.