The study addresses the ability of luminous bacteria Photobacterium leiognathi Boisvert et al. and Photobacterium phosphoreum (Cohn) Beijerinck to synthesize polyesters of hydroxycarbon acids (polyhydroxyalkanoates, PHAs) as storage macromolecules. The screened strains widely vary in their PHA productivity. Ph. leiognathi (but not Ph. phosphoreum) produces PHAs containing monomers of 3-hydroxyvaleric acid and, in some cases, 3-hydroxyhexanoic acid, in addition to common monomers of 3-hydroxybutyric acid. All studied strains of Ph. phosphoreum produce pure poly-3-hydroxybutyrate only. In the case of Ph. leiognathi, addition of valeric acid as substrate can increase the amounts of medium-chain-length hydroxy acids contained in the produced polymers. The results suggest a conclusion that luminous microorganisms of Photobacterium genus can be considered as producers of multi-component PHAs