The effect of exogenous administration of antioxidant (Anttox) on the course of B. hominis in experimentally infected mice was studied. B. hominis isolates were obtained from 10 gastrointestinal symptomatic adult patients. Three groups of 30 infected mice (3/isolate) were used. GI was untreated infected, GII was treated by antox for 4 weeks after infection diagnosis (treatment strategy), and GIII antox treated by for 4 weeks before infection (prophylactic strategy). Mild pathological changes were detected on 13.4%, 19.9% & 86.8% of mice in Gs I, II & III, respectively. Moderate pathological changes were found in 29.9%, 26.6% & 6.6% of mice in Gs I, II & III, respectively. While, the majority of severe pathological changes were in Gs I & II (56.7% & 53.5%) as compared to GIII (6.6%). Meanwhile, 86.8% of mice in GIII had B. hominis forms > 10/high power field compared to 3.3% in Gs I & II, respectively. Although 19.8% of mice in GII were positive for B. hominis by direct smear, no growth resulted in vitro and all the forms were non-viable by using neutral red stain. All the differences were statistically significant. So, antioxidant exacerbated B. hominis intensity but it decreased the pathological changes.