This study aimed to determine the incidence of giardiasis in sheep of Anbar Province by inspecting 660 faecal specimens. An examination using a flotation technique confirmed the presence of Giardia lamblia in 46.2 % of specimens. The gender had no significant effect on the infection percentage, as it was similar for males (46.9 %) and females (45.4 %). The highest infection rate was 61.7 % for animals aged 1 month to 2 years. During the summer, the infection rate was 61.8 %, whereas it was 27.8 % during the winter, which clearly depicts the seasonal variation in the parasite infestation. The current study systematically evaluated the impact of Portulaca oleracea against G. lamblia. An aqueous extract was prepared by macerating dried the plant material in distilled water, yielding a 15 mg/mL stock solution, which was serially diluted to concentrations of 1.5, 3.0, 4.5, 6.0 and 7.5 mg/mL, the extract exhibited a concentration-dependent inhibitory effect over 48 hrs, with a concentration of 7.5 mg/mL significantly reducing parasite viability. However, complete eradication was not achieved and requires statistical confirmation. As cytotoxicity assays on host cells were not conducted, the safety of the extract remains unverified. Giardiasis was found to be widespread among sheep in Anbar Province. In contrast, the extract demonstrated promising in vitro anti-Giardia activity. Further studies, particularly those examining cytotoxicity and in vivo evaluations, are necessary before recommending it as an alternative treatment.