Background: There is no validated scale to assess neurodevelopment of infants and children in Sri Lanka. The Bayley III scales have used widely globally but it has not been validated for Sri Lankan children. We administered the Cognitive and Motor Scales of the Bayley III to 150 full-term children aged 6, 12 and 24 months from the Gampaha District of Sri Lanka. We compared the performance of Sri Lankan children 6, 12 and 24 months of age on the cognitive and motor scales of the Bayley III with that of US children. Results: Compared to the US norms, at 12 months, Sri Lankan children had significantly higher cognitive scores and lower gross motor scores, and at 24 months significantly lower cognitive scores. The test had a high test-retest reliability among Sri Lankan children. Conclusions: There were small differences in the cognitive and motors scores between Sri Lankan and US children. It is feasible to use Bayley III scales to assess neurodevelopment of Sri Lankan children. However, we recommend that the tool be validated using a larger representative sample of all population groups. © 2014 Godamunne et al.; licensee BioMed Central Ltd.