Abstract: 　Objective To study morphology of different stage Blastocystis haminis (B.h) for establishing a base in the research of life cycle and pathogenicity of B. h and providing information for clinical laboratory. Methods B. h from diar-rheal patients was continuously cultured in LES medium, and morphology of B.h was studied with iodine and iron hematoxylin staining under light microscope. Results The vacuolar, granular, amoeboid and cyst forms of B. h and transformation among the forms were observed microscopically. Conclusion Among different forms, the vacuolar and granular forms were often seen clinically and the vacuolar form can transform to cysts.

Key words: Blastocystis hominis, diarrhea, medium, morphology