Abstract : The present study included microscopic and molecular diagnosis of Entamoeba histolytica in the stool samples of patients attended to Al Alawia Teaching Hospital and Central Child Teaching Hospital in Baghdad Governorate, Iraq for the period from 1st October 2020 to 1st August 2021. The fecal samples were examined microscopically by a direct wet mount then the fecal samples were molecularly examined using specific primers to detect four virulence factors possessed by the parasite E. histolytica. Titanium dioxide nanoparticles were synthesized from Pseudomonas aeruginosa which producing Pyocyanin pigment as a reducing agent to form Titanium dioxide nanoparticles. The biosynthetic titanium dioxide was characterized using several tests (XRD, scanning electron microscopy FE-SEM, Fourier transform infrared spectroscopy, FTIR, UV visible spectroscopy). Histological changes in mice infected with E. histolytica, microscopic examination revealed severe amoebic colitis, which was characterized by thickening of the mucous layer with epithelial sloughing and the appearance of small and multiple ulcers in mucous layer as well as bleeding and congestion. Trophozoites were also observed in the enlarged sections in the remnants of sloughed and necrotic mucosal and epithelial cells. Our results showed that treatment with biosynthesized Titanium dioxide nanoparticles has a significant role in restoring the normal appearance of colonic epithelial and mucous cell so this shows the effectiveness of this Nanomaterial as an antiparasitic in curing the genes responsible for parasite virulence factors and thus reducing pathogenicity.