AIM: To observe the effect of praziquantel on Cysticercus cellulosae in vitro. METHODS: After the Cysticercus cellulosae were incubated with praziquantel for 2, 4 and 6 h, the in vitro effects were observed by scanning and transmission electron microscopy. RESULTS: The structural and celullar changes of Cysticercus cellulosae under the action of praziquantel included the convulsion and deformity of the cyst body, corrosion of the body surface. Necrosis of the tegument and subtegument, and dissolution of the endoplasmic reticulum and ribosome. CONCLUSION: Praziquantel exerts strong action against Cysticercus cellulosae.