Microsporidia belongs to the Microspora order and is classified as one of the most commonly known species, more than 140 genera and 1200 species have been identified. This parasite has the ability to infect many vertebrates and invertebrates. Microsporidia is a spore-bound intracellular parasite that enables them to survive under severe environmental conditions and pathogenicity. In general, the protozoa is common in people with immune deficiency and can cause acute and deadly infections. This study is a review article from most articles and internal and external books that have examined this parasite. The purpose of this study is to review the microsporidia protozoa and to evaluate the prevalence, diagnosis and treatment of Microsporidiosis in HIV positive patients.