Poly-beta-hydroxybutyrate (PHB) was recently shown to be produced in genetically engineered plants which expressed the genes from Alcaligenes eutrophus responsible for the formation of PHB from acetoacetyl-CoA. The transgenic plants accumulated PHB as granules which were similar in size and appearance to the bacterial PHB granules. These observations suggest that large scale production of PHB and other polyhydroxy-alkanoates in genetically altered crop plants may be feasible.