Abstract: Objective To confirm existence of Sarcocystis suihominis and possible transmission cycle between human and pigs. Methods Based on the human-pig-human infection cycle of Sarcocystis suihominis ， feces of naturally infected pigs were collected and over 10 000 sporocysts were received by flotation technique， which were mixed with fodder to infect a normal pig. Fresh pork meat containing mature sarcocysts was chopped into pieces and swallowed by a volunteer （the first author of this paper） with about 71 000 sporocysts. Symptoms and development of the parasites after infection were observed. Results The volunteer showed abdominal distension in about 5 hours after infection， with watery diarrhea 13 times from the 8th to 36th hour， vomiting 4 times， chilling and fever with a temperature of 38.5℃， dizziness， headache， joint and muscle ache， epigastralgia， and anorexia. Unsporized sporocysts were found in the faces 10 days after infection and sporocysts appeared on the 12th day. The average size of sporocysts was 11.9（8.8-14.5）μm×9.2（7.5-12.5） μm. The infected pig showed a slight anorexia， fatigue， constipation， hair loosen in 5～8 days after infection， and returned normal on the 17th day. The average size of the sarcocysts was 299.2（175-575）μm×62.3（30-102.5）μm. Size of bradyzoites was 11.5（9.5-13.5）μm×4.1（2.8-5.0）μm. The volunteer was treated with acetylspiramycin for 15 days（0.2 g/time， 4 times/d） after 46 days of infection， and fecal examination turned negative 30 days later. Conclusion There is a man-pig cycle for Sarcocystis suihominis in Guangxi.

Key words: Sarcocystis suihominis, Infection, Guangxi