Anorchia, or the "vanishing testis syndrome," is characterized by the absence of testis in a 46,XY individual with a male phenotype. The etiology is unknown; however, the familial occurrence of the disease and the association of this phenotype with 46,XY gonadal dysgenesis has led to the suggestion that genetic factors, which play a role in testicular determination, may be involved. Alternatively, exploratory laparoscopy has suggested that anorchia may be caused by a prenatal testicular vascular accident associated with torsion during testicular descent. We screened a cohort of 14 boys with bilateral anorchia for mutations in the Y chromosome-linked testis-determining gene SRY (sex-determining region, Y chromosome); in the gene necessary for correct testicular descent, INSL3; and in the gene of its receptor (LGR8). Mutations in the INSL3 gene and the LGR8 T222P mutation are known to cause cryptorchidism. We confirmed previous reports that mutations in the SRY gene are not associated with anorchia. Although a common polymorphism was identified in the INSL3 gene, no mutations were observed. The recurrent T222P mutation in the LGR8 gene was not found in any of the patients. These data show for the first time a lack of association between genetic factors necessary for correct testicular descent and anorchia.