Many laboratories currently diagnose B. hominis infections by looking for the presence of vacuolar forms in faeces and the amoeboid form in diarrheal stools. This study aimed to investigate the best direct method for diagnosis of Blastocystis hominis and to study different morphological forms of the parasite. The study was carried out on one thousand and two hundred diarrheic stool samples. All samples were examined using direct smear, iodine stained smear, trichrome stained smear ,formalin–ether concentration techniques, and in vitro cultivation using Jone’s medium. Using direct smear, B. hominis was detected in 42 cases (3.5%) with a sensitivity (28.4%) and specificity (100%).Iodine stained smear detected 72 positive cases (6%) with a sensitivity (48.7%) and specificity (100%). Formol ether concentration technique detected 120 positive cases (10%) with a sensitivity (81.1%) and specificity (100%). Trichrome stained smear detected 148 positive cases (12.3%). In vitro cultivation using Jone’s medium detected 274 positive cases (22.8%) which was the highest number among all different diagnostic methods with a sensitivity (100%) ,specificity (88%), PPV (54.1%) and NPV (100%). The vacuolar form of the parasite is the most common form found in all methods used in this study followed by cyst form then granular form then the amoeboid form which was detected only in culture It was found that, 49 blastocystosis cases had mixed infection with other intestinal parasites. Giardia lamblia was the most frequently associated parasite with B. hominis.