RESUMEN
INTRODUCTION: Complete Androgen Insensitivity Syndrome (CAIS) is a X-linked recessive disorder characterized by a complete resistance of the Androgen Receptor (AR) to androgens. As a result, affected individuals present complete female external genitalia, but are genetically male with a 46, XY karyotype. The typical presentation for this syndrome is either inguinal swellings in a new born or infant, or primary amenorrhoea in an adolescent. CAIS is commonly diagnosed in one of these clinical scenarios, although recently prenatal diagnosis has been reported. We present a case of a phenotypically female infant with an inguinal swelling, which was biopsied and exposed as testicular tissue, doing the diagnosis of CAIS. A review of the literature on this disorder is made.