A cross-sectional study to examine the association of giardiasis with protein-energy malnutrition, vitamin A deficiency and iron deficiency anaemia was conducted among Orang Asli children in Selangor, Malaysia. A total of 281 children aged 2-15 years were studied. The data were collected using structured questionnaires, anthropometric measurements and laboratory analysis of blood and faecal samples. The results showed that 24.9% of the children were infected with Giardia duodenalis, while 56.5, 61.3 and 15.1% had significant underweight, stunting and wasting, respectively. Giardiasis was statistically identified as a strong predictor of significant wasting in this study population.