Numerous studies have revealed the presence of oxidative stress in parasitic infections. However, such studies were lacking in the Malaysian population. Previously, we have provided evidence that oxidative stress is elevated in Malaysians infected with intestinal parasites. Stool examinations revealed that about 47.5% of them were infected with the polymorphic protozoa, Blastocystis hominis. However, they were found to have mixed infection with other intestinal parasites.