The purpose of this study was to estimate genetic and phenotypic parameters for gestation length and birth weight in Bonsmara cattle in South Africa. A total of 26962 gestation length and birth weight records for the period 1989 to 2000 were available. The sources of non-genetic variation for gestation length and birth weight were sex, herd x year x season (HYS) and age of dam (linear and quadratic). A direct heritability of 0.38 was estimated for gestation length and 0.23 for birth weight. Maternal heritability estimates were lower, 0.09 for gestation length and 0.11 for birth weight. A direct genetic correlation of 0.40 and a maternal genetic correlation of 0.57 were obtained between gestation length and birth weight, which is favourable. This indicates that there will be a correlated response in gestation length when there is selection on birth weight or vice versa.