this invention relates to polymer production and in particular to a novel copolymer and a process for microbiologically producing the same . more specifically this invention provides for a poly - 3 - hydroxyalkanoate that includes medium length 3 - hydroxyacyl monomers and a process comprising culturing a microorganism with a medium chain fatty carbon source and a fatty acid oxidation inhibitor . this invention allows the use of microorganisms which normally incorporate only short chain fatty acids to produce phas containing short and medium chain 3 - hydroxyacyl monomers . the purpose of this invention is to produce a more versatile pha polymer which includes c6 , c7 and / or c8 3 - hydroxyacyl monomers .