A syndrome found in a person who has X,Y chromosomes, but who is resistant to androgens (male hormones). As a result, the individual has some or all of the physical characteristics of a female.

The syndrome is divided into two main categories: complete and incomplete. Complete testicular feminization results in someone who looks outwardly female. In the incomplete forms of testicular feminization syndrome, the degree of sexual ambiguity runs the gamut.

The syndrome is caused by various genetic mutations on the X chromosome. The mutations make a developing male baby unable to respond to androgens. (Androgens are responsible for male physical characteristics.)

If the androgen insensitivity is complete, this prevents the development of the penis and other male body parts. The child is born appearing to be a girl. The complete form occurs in as many as 1 in 20,000 live births.

Different degrees of androgen resistance can result in a wide variety of clinical outcomes. Incomplete testicular feminization can include other disorders, such as Reifenstein's syndrome (also known as Gilbert-Dreyfus syndrome or Lubs syndrome), which is associated with hypospadias, gynecomastia, and cryptorchidism. Also included in the broad category of incomplete testicular feminization is infertile male syndrome, which is sometimes due to an androgen receptor disorder.