Over an 18 month period, 34,495 livebirths were delivered in the Kuala Lumpur Maternity Hospital. 36 neonates (1.044 per 1000 livebirths) had Down's syndrome. The observed rates of Down's syndrome per 1000 livebirths by single year intervals of maternal age were calculated. By using the discontinuous slope model, our study showed that the incidence of Down's syndrome among the Malaysian liveborns increased markedly when the maternal age exceeded 35 years. This study also suggested that the Malay mothers had increased risk of producing babies with Down's syndrome at a later age than the Chinese and the Indians. However, a larger number of babies in each racial group needs to be studied to confirm this.