To observe the effects of simulated microgravity on beta islet cell culture, we have compared the survival rates and the insulin levels of the isolated rat islet cells cultured at the micro- and normal gravity conditions. The survival rates of the cells cultured were determined by acridine orange-propidium iodide double-staining on day 3, 7 and 14. The morphology of the cells was observed by electron microscopy. Insulin levels were measured by radioimmune assays. Our results show that the cell number cultured under the microgravity condition is significantly higher than that under the routine condition (P<0.01). Some tubular structure, possibly for the transport of nutrients, were formed intercellularly in the microgravity cultured group on day 7 after the cultivation shown by transmission electron microscopy. There were also abundant secretion particles and mitochondria in the cytoplasma of the cells. Scanning electron microscopy showed there were holes formed between each islets, possibly the connecting points with the nutrients transport tubules. The microgravity cultured group also has the higher insulin levels in the media when compared with the control group (P< 0.01). Our results indicate that microgravity cultivation of islet cells has advantages over the routine culture methods.