The purpose of this study was to investigate the socioeconomic, biological and behavioural factors influencing low birth weight and prematurity in Botswana. Data were from the Botswana Obstetric Record covering the years 1990 to 1995, and were analysed with both descriptive statistics and multivariate analysis. The study found that the major positive risk factors for low birth weight were: late and less frequent attendance of antenatal care services, having experienced pregnancy termination before, low or no education, unmarried motherhood and place of birth. With regard to prematurity, age, late and less frequent attendance of antenatal care services, unmarried motherhood and place of birth were found to be the major positive risk factors. The importance of early and regular antenatal care attendance, marriage and place of birth cut across both low birth weight and prematurity.