Production of poly(3-hydroxybutyrate) (PHB) from starch was investigated in flask, batch, and fed-batch cultures of Azotobacter chroococcum. In flask culture, PHB content increased up to 74% of dry cell wt with increasing culture volume. In batch culture, PHB content increased to 44% with O-2 limitation. In fed-batch culture, cell concentration of 71 g/l with 20% PHB was obtained without O-2 limitation, whereas cell concentration of 54 g/l with 46% PHB was obtained with O-2 limitation.