Molecular genetic study of androgen insensitivity syndrome is now easier by the development of powerful molecular tools. Complementary DNA of the androgen receptor gene has been recently cloned and sequenced. The development of cDNA probes gave the opportunity to study DNA restriction fragment length polymorphisms of patients with complete or partial androgen insensitivity syndrome. These studies demonstrated that deletions are rarely observed. Using PCR and sequencing of exons, several groups described point mutations within the androgen receptor gene. Enzymatic amplification along with denaturing gradient gel electrophoresis and single strand conformational polymorphism study allowed the description of new mutations. These powerful tools together with mRNA study, expression of muted gene, anti-receptor study had also permitted to analyze correlations between structure-function activity of the androgen receptor gene in patients with androgen insensitivity syndrome.