Following growth of Alcaligenes sp. SH-69 on glucose as a sole carbon source for the production of poly-beta-hydroxyalkanoates (PHAs), relatively low levels of levulinic acid (LA) were detected. Experiments were carried out in batch and continuous culture, and the effects of LA addition on growth and PHA synthesis were determined. Significant stimulatory effects were observed, greater than those for propionic acid addition. In N-limited two stage continuous culture, a maximal PHA content of 38.3% (w/w) was achieved with a polyhydroxyvalerate (PHV) content of 23.5% (molar basis) at D=0.078 1/h. This resulted from, the controlled addition of LA at 0.5 g/L/h in the presence of excess glucose.