Background: Giardiasis is one of the most common intestinal parasitic infections causing diarrheal illness in humans worldwide. Detection of Giardia intestinalis is traditionally performed by microscopic examination of stool specimens. Nitroimidazoles group (metronidazole and tinidazole) are conventional drugs of choice for treatment of Giardiasis with a cure rate of higher than 90%. All of these drugs may lead to numerous adverse reactions, require long duration therapy, and none of them is absolutely safe for use during pregnancy. Objective: This study was undertaken to evaluate the performance of the ELISA coproantigen for the diagnosis of Giardiasis and to compare the efficacy and safety of Nitazoxanide versus Metronidazole in the treatment of giardiasis. Subjects and methods: A total of 350 children, aged 6-12 years, of both sexes were randomly selected for parasitological investigation using direct wet mount and formol-ether concentration techniques. The Giardia infected cases and 20 free of parasites were subjected to ELISA coproantigen test. Eighty cases infected with Giardia intestinal is were divided randomly into 2 equal groups: Group (1) were given nitazoxanide (200 mg twice daily for 3 days respectively), and Group (2) were given metronidazole (20 mg/kg thrice daily for 7 days). To evaluate the effectiveness of the therapy, at least three stool samples from all cases were examined after completion of the treatment. A standardized questionnaire was used to record Clinical symptoms of the patients in each group prior to and after treatment. Results: The prevalence of giardiasis in our study was 23.7% . In our study, enzyme linked immunosorbent assay for coproantigenic detection of G. intestinalis has a sensitivity of 94.9% and a specificity of 85.7% with PPV of 92.5%, and a NPV of 90 %. The two treated groups were similar with respect to sex and mean age. The cure rate was 95% and 85% for Nitazoxanide and Metronidazole respectively with  statistically significant difference. Conclusion: The results of this study suggested that coproantigenic technique by ELISA test is suitable for use in testing a larger number of samples, especially for screening persons in regions where G. intestinalis is a common wide pathogen. Also, it confirms the efficacy and safety of nitazoxanide as a 3-day treatment of giardiasis in children.