A simple and effective method for the recovery poly(3-hydroxybutyrate) [P(3HB)] directly from high cell density culture broth with no pretreatment steps has been developed. This method consists of direct addition of sodium dodecyl sulfate (SDS) to the culture broth, shaking, heat treatment, and washing steps. When the SDS/biomass ratio was higher than 0.4, the purity of recovered P(3HB) was over 95% for various cell concentrations of 50-300 g dry cell l(-1), with the highest value of 97%. The recovery of P(3HB) was over 90% regardless of cell concentration and SDS dosage (SDS/biomass ratios, 0.1-0.7). One g SDS digests 0.72 g non-P(3HB) cell materials. The reduction in molecular weight, due to degradation of P( 3HB) by SDS, was negligible.