Poly(3-hydroxybutyrate) (PHB) was produced by fed-batch cultures of Ralstonia eutropha with phosphate limitation under different glucose concentrations. When glucose was kept at 2.5 g l(-1), cell growth and PHB synthesis were limited due to the shortage of carbon source but a higher PHB content occurred in the cell-growth stage. This shows that a low glucose concentration is favorable for PHB accumulation in R. eutropha. PHB obtained with glucose at 9 g l(-1) is 1.6 times that obtained with 40 g l(-1). When glucose was in the range of 9 to 40 g l(-1), PHB concentration and productivity decreased significantly with the increase of glucose concentration. The highest PHB productivity was obtained with glucose at 9 g l(-1).