Male pseudohermaphroditism can occur either as a result of inadequate fetal androgen secretion or ineffective androgen action. Partial androgen insensitivity syndrome is related to a decrease in the binding capacity of target cells androgen receptors. However, the biochemical expression of these syndromes is variable: although a low concentration of androgen receptors is observed in 75% of the cases, a normal binding capacity is sometimes reported. If the presence of androgen receptors is necessary for hormonal action, it is not sufficient since the receptor has to conserve its functional integrity. Several qualitative abnormalities of the androgen receptor have been described and could thus explain the disturbance in the androgen mechanism of action. The study of androgen-dependent proteins and other androgen-receptor "markers" should offer the clinician a better management of partial androgen insensitivity and allow, in amniotic or trophoblastic cells, a prenatal diagnosis of androgen resistance in high-risk families.