Information on the birthweight and gestational age of previous siblings is usually dependent upon maternal recall. This information is of importance in assessing the current risk of perinatal morbidity and mortality. The validity of maternal recall of birthweight and gestational age of 880 children born to 97 multiparas was examined by comparison with hospital records. About 75% of all reported birthweights were accurate to within 100 g and a similar proportion of reported gestational ages was correct to within 1 week. Recall was most accurate for most recent births as well as for earliest births and was not related to maternal age or education. There was a tendency for the smallness of low birthweight infants to be exaggerated by mothers. We conclude that within defined limitations, maternal recall of birthweight and gestational age of previous children is sufficiently accurate for clinical and even for epidemiological use.