Human sexuality has three main roots: biological, motivational-affective-relational, and cognitive. Unfortunately, in women, the biological dimension is usually disregarded. Hormones are necessary, but not sufficient, factors to maintain a satisfying human libido. In women, oestrogens prime the central nervous system, acting as neurotrophic and psychotrophic factors throughout life. They also prime the sensory organs, including the skin with its sebaceous and sweat glands, which are the key receptors for external sexual stimuli. Oestrogens are also the 'permitting factors' for the action of vaso-intestinal peptide, the key neurotransmitter involved in the endothelial and vascular changes leading to vaginal lubrication. Other factors, such as medication, alcohol and other health problems, can modify the biological impact of hormones on libido. Depression may cause a progressive decline in interest in sexual behaviour leading to low libido, difficulty in sexual arousal, secondary anorgasmia and/or frank sexual aversion. Increasing attention of doctors towards the sexual problems of women will dramatically improve female quality of life, especially during difficult periods of transition.