The main causes of female infertility are anovulation and anatomical causes such as obstruction in the genital tract. Many aspects of female reproductive function are strongly influenced by genetic factors. Androgen insensitivity syndrome is an X-linked disorder characterised by variable defects in virilisation of 46,XY individuals. A genetic contribution to spermatogenic failure is indicated by several families with multiple infertile or subfertile men. Klinefelter syndrome (47,XXY) is the most frequent cause of gonosomic anomalies, occurring in 0.1-0.2 % of newborn males. Chromosomal translocations are found with a frequency 8-10 times higher in infertile men and may be acrocentric Robertsonian translocations or reciprocal translocations. The prevalence among infertile men is high, from 5 % in those with severe oligozoospermia to 10 % in those with azoospermia. Understanding of the genetic basis of infertility is likely to increase dramatically in the future. New technologies are available that permit high-throughput detailed genetic analysis.