• The genetic and environmental antecedents of two clinically distinct somatoform disorders were compared in 859 Swedish women adopted at an early age by nonrelatives. The characteristics of both the biological and adoptive parents of high-frequency "somatizers" were different from those of diversiform somatizers. The risk of diversiform somatization was increased in the adopted-away daughters of men treated for male-limited (type 2) alcoholism, but not in daughters of milieu-limited (type 1) alcoholics. In contrast, the biological fathers of high-frequency somatizers often had a history of recurrent convictions for violent crimes since adolescence, but no treatment for alcoholism. Similarly, alcohol abuse by the adoptive father was associated with increased risk of diversiform but not high-frequency somatization. Thus, highfrequency and diversiform somatization are not only clinically distinct, but also have different genetic and environmental backgrounds. The association of diversiform somatization with male-limited alcoholism, and not with milieu-limited alcoholism, also provides independent support for our earlier distinction between these two types of alcoholism.