Batch cultivation of Ralstonia eutropha NRRL B14690 attained 21 g biomass l(-1) and 9.4 g poly(beta-hydroxybutyrate) l(-1) (0.45 g PHB g(-1 )dry wt(-1)) in 60 h. Repeated batch operation (empty-and-fill protocol) to remove 20% (v/v) of the culture broth and to supplement an equal volume of fresh media resulted in 49 g biomass l(-1) and 25 g PHB l(-1) (0.51 g PHB g(-1) dry wt(-1)) with an overall productivity of 0.42 g PHB l(-1 )h(-1 )in 67 h. In the two cycles of repeated batch fermentation there was a 3-fold increase in productivity as compared to batch.