The cord blood glucose-6-phosphate dehydrogenase (G6PD) enzyme activity of 262 normal term Malaysian neonates (92 Malays, 96 Chinese and 74 Indians) was quantitatively determined by the World Health Organisation method. Analysis of variance for the levels of G6PD enzyme activity by ethnic origin and sex showed that there was a significant difference between mean levels of enzyme activity in the three ethnic groups (P = 0.03) but no difference between the sexes (P = 0.36). Multiple range analysis showed that Malays had significantly higher mean levels of G6PD enzyme activity than those of Chinese (P = 0.01). There was no significant difference between the mean levels of G6PD enzyme activity of Chinese and Indians (P = 0.52), nor was there any difference between those of Malays and Indians (P = 0.08). The difference in levels of G6PD enzyme activity among the different ethnic groups could be due to the existence of different G6PD variants.