A water buffalo (Bubalus bubalis) was fed 5.0 × 10⁵ Sarcocystis hominis sporocysts from a human volunteer who had ingested S. hominis cysts from naturally infected cattle. A necropsy was performed on the buffalo 119 days after inoculation, and a large number of microscopic sarcocysts (∼5,000/g) were found in skeletal muscles. Ultrastructurally, the sarcocyst wall from buffalo muscles has upright villar protrusions measuring about 5.6 × 0.8 μm with numerous microtubules that run from the base to the apex. Sarcocysts from this buffalo were infective to 2 human volunteers, confirming their identity as S. hominis. Therefore, we believe that buffaloes can act experimentally as the intermediate host for S. hominis.