The attitudes of women of reproductive age to IVF therapy and human embryo research were investigated. A questionnaire was given to 1920 consecutive women attending clinics for family planning (1050), ante-natal care (705) and infertility (165). This paper reports the analysis of 1701 returned questionnaires, all from women of reproductive age. The great majority (94%) were in favour of IVF treatment. Sixty-seven percent approved of research on human embryos up to 14 days to improve IVF treatment, and a further 10% supported research on embryos designed to avoid birth defects. The majority (79%) thought women should be allowed to donate ova for research. The social characteristics of the infertility group were similar to those of the ante-natal group except for lower parity. In the family planning and ante-natal groups attitudes were not related to age, social class or parity, but were influenced by religious beliefs.