This paper describes the last part of a study on the long-term psychosocial consequences of caesarean delivery. One group of 103 primiparous caesarean delivered women and one control group of 103 women delivered vaginally were followed from delivery to the children's fourth birthday. Previous assessments were made at birth, two months and one year later (Garel, M., Lelong, N. and Kaminski, M. (1987) J. Psychosom. Obstet. Gynecol., 6, 197-209 and (1988) Early Hum. Dev., 16, 271-282). Four years after delivery, 58 mothers of the caesarean group and 50 mothers of the control group returned a completed questionnaire. The questionnaire included questions about subsequent pregnancies and mother's and child's general state of health. The comparisons between respondents and non-respondents showed no significant difference with regard to social and medical factors. As far as possible, factors which might have interfered with the mothers' and children's conditions were controlled in the analysis. There was no association between the method of delivery and the mother's overall state of health. However, after a caesarean section, mothers tended to have fewer children and more difficulty in conceiving. Four years after delivery, mothers in the caesarean group reported fatigue more frequently than control mothers. Five mothers (9%) consulted a psychiatrist, none in the control group (P < 0.09). Between one and four years, caesarean born children had more hospital admissions but their overall behaviour and development, as reported by the mothers, was not different from those of children in the control group. © 1990.