PIP: 615 Kenyan women who had experienced 2407 pregnancies and 1792 birth intervals were interviewed who had delivered at the Kenyatta National Hospital during the months of June and July, 1985. Birth intervals that were 25-36 months long were associated with the most favorable pregnancy outcome. Poor pregnancy outcome was followed by very short birth intervals with more than 75% of the birth intervals being 24 months long or less. When no contraceptives were used 58% of the birth intervals were 24 months long or less compared with only 25.5% when contraceptives were used. Breastfeeding alone is not very effective in prolonging the birth interval since 33.4% of women resumed regular menstruation by 4-6 months when they are still breastfeeding. Only 31% of married women were abstinent by 3 months postpartum and therefore in this group of women abstinence played no role in prolonging the birth interval. It is apparent that the use of effective modern contraceptive methods, good obstetrics and neonatal care and adequate breastfeeding are the key measures that can ensure the optimum birth interval and hence the most favorable pregnancy outcome.