The diagnosis of female androgen deficiency syndrome is suggested by complaints of a diminished sense of well being, persistent unexplained fatigue and decreased sexual desire, sexual receptivity and pleasure in a woman who is oestrogen-replete and in whom no other significant contributing factors can be identified. The diagnosis is supported by the finding of low circulating concentrations of free testosterone. Barriers to its recognition include the non-specificity of the symptoms and methodological problems due to insensitive testosterone assays. Barriers to its treatment include the unavailability of satisfactory forms of testosterone for administration to women and lack of data regarding long-term safety. Although several conditions lead to clear-cut androgen deficiency, such as hypopituitarism, adrenal and ovarian insufficiency, glucocorticoid therapy and use of oral contraceptives and oral oestrogens, it is important for clinicians to recognise that in normal women, androgen levels decline by 50% from the early 20s to the mid 40s, and hence age-related androgen insufficiency may occur in women in their late 30s and 40s, as well as postmenopausally. Satisfactory measurements of free testosterone requires a sensitive and reliable assay for total testosterone, and quantitation of sex hormone binding globulin, from which free testosterone is readily calculated. Adverse effects of testosterone treatment are few if replacement is monitored to achieve physiological circulating testosterone concentrations. Currently, available methods include testosterone implants and testosterone creams, and transdermal patches and sprays are in development.