Background: Blastocystis hominis is recognized as a common intestinal PARASITE. Some studies have reported the effect of phenotypic, serologic, and biochemical indices on the PARASITEs’ pathogenic characteristics. Objectives: This study aimed to introduce B. hominis as a pathogen, trying to change views about this PARASITE and introduce it as a PARASITE important in medical sciences. Methods: An open-ended, language-restricted (English) search was conducted in MEDLINE (PubMed), CINAHL, Scopus, and the Cochrane Library databases (from 1990 to 2018) using specific search criteria to identify Blastocystis spp. Results: The search of the literature retrieved 158 published articles on Blastocystis spp. Among these articles, the ones related to the pathogenicity of B. hominis were selected for further investigations. Results obtained in this study showed that the number of articles within five-year periods had an increasing trend. Also, studies of B. hominis have mainly investigated its pathogenic characteristics, accounting for 37. 34% of the studies. Conclusions: This study showed comprehensive reasons for proving the pathogenesis of the PARASITE. It is hoped that further studies would fill the existing gaps regarding this PARASITE and identify its true identity as a medically important PARASITE.