Many studies report unusually high rates of gallbladder cancer among all American Indians and among Hispanic Americans in the Southwest and California. It has been suggested that there is a strong genetic component to the development of this cancer in American Indians and that the high rates among Hispanics are a result of genetic admixture with Indian groups. In this paper, we review the epidemiologic characteristics of gallbladder cancer in New Mexico's Hispanic population. We discuss the genetic study of the residents of the Abiquiu area of Rio Arriba County in northern New Mexico where the incidence of gallbladder cancer in white residents is significantly higher than that in any other county of the state. The Abiquiu population has a high degree of Indian ancestry, is genetically isolated, and shows close inbreeding. This combination has produced elevated frequencies of the allele or alleles predisposing to gallbladder cancer. Two familial aggregations of this disease, the first such aggregations to be reported, appear among these people.