STUDY OBJECTIVE: To examine the association between body height, body mass index (BMI), and mortality in fertile women of childbearing age. DESIGN: A prospective cohort study with a 29 year mortality follow up. SETTING AND PARTICIPANTS: A cohort of women (n = 11,997) expected to deliver during 1966 in two northern provinces of Finland. Data on height and pre-pregnancy weight, collected with those on sociodemographic characteristics and smoking by questionnaire at the third trimester, were provided by 91% of the participants. Follow up for mortality using national registries was from delivery until the end of 1994. MAIN RESULTS: Height had a 'U' shaped association with total mortality over the whole follow up time. In women who were shorter than average, the death rate from cardiovascular diseases was increased and in taller women this was true for tumours. Compared with the women of 'normal weight' (BMI 21 to