Electrofusion of evacuolated (N. Tabacum L. cvs. Gexin no1) and vacuolated (N. Rustic) tobacco mesophyll protoplasts was performed on the Chinese spacecraft (Shenzhou No. 4, from 30th Dec. 2002 to 6th Jan. 2003). The results showed that the frequency of bi-nucleated and multinucleated protoplasts was significantly increased under microgravity. Compared with the control samples incubated on the ground, the viability of protoplasts incubated in space was much higher. In addition, the influence of altered gravity on carbohydrates was also observed. These results confirmed the effect of microgravitation on electrofusion of plant cell protoplasts.