Problems affecting the female prison population have become increasingly acute. In response to a spirit of 'toughness' in penal policy, the number of women prisoners has grown sharply and more women are being sent to prison despite arguments in favour of decarceration and alternative sanctions. In prison, women make greater demands on prison health services and are generally considered to carry a greater load of physical and mental ill-health than their male counterparts. However, a gender-sensitive theory based on an understanding of the relationship between women's health and women's imprisonment has not been formulated. Health is a complex phenomenon of inseparable physical, mental and social processes. Research conducted in three women's prisons in England set out to explore the relationships between these processes. Data were generated from group discussions, in-depth interviews, a questionnaire survey and observation and participation in 'the field'. The findings suggest that women's imprisonment is disadvantageous to 'good' health. Deprivations, isolation, discreditation and the deleterious effects of excessive regulation and control all cause women to suffer as they experience imprisonment. These are not medical problems. Yet, they often become so once they cause, as they inevitably do, stress and anxiety. The woman prisoner who finds herself unable to cope is likely, eventually, to come into contact with the prison medical enterprise where a medicalised view of suffering de-politicises the significance of women's distress. Social and cultural factors in women's pre-prison and prison lives interact to influence their health and their freedom to choose 'correct' health behaviours. While different in degree, the problems facing women prisoners are of the same kind as those they face in their outside lives and the same kinds of 'solutions' are adapted to deal with them. Such solutions often have unforeseen consequences which can intensify the pains of imprisonment and be further prejudicial to health. These findings raise questions about the philosophies underpinning current models of prison health care where the benevolent aims of 'health promotion' may become extremely punitive.