46,XX testicular disorder of sex development is a rare cause of male infertility. There is a disagreement between the manifested sexual phenotype (male) and the genotype (female). It occurs in males with 46,XX karyotype who may have normal or ambiguous male genitalia, testosterone deficiency and infertility. With adequate hormonal treatment, the chance of having a good quality of life is high. In the diagnosis, the genetic study is fundamental for the identification of the gene that causes the disorder. The role of SRY gene is important because it allows classifying these males into two groups: those with SRY gene, which activates male sexual differentiation, translocated from Y chromosome to X (SRY-positive), and those without this translocation (SRY-negative). 80-90% of cases are SRY-positive. In the 1020% SRY-negative it is difficult to identify the gene responsible for the alteration. This would indicate the involvement of other genes linked to the X chromosome. This is a review of the first case of SRY-negative 46,XX testicular disorder of sex development with complete masculinization reported in Basque Country in which the cause of the disorder is being investigated, even without specifying.