Hydroxyalkanoates (HA) can be widely used as chiral building blocks for the synthesis of fine chemicals. In this study, HA monomers were produced directly using genetic engineering techniques. The recombinant E. coli HB101 harboring beta-ketothiolase (PhbA) and acetoacetyl-CoA reductase (PhbB) of Ralstonia eutropha was found to be able to produce more than 1 g L-1 of 3HB monomer extracellularly after 48 h of fermentation. Heterogenous expression of (R)-3-hydroxydecanol-ACP: CoA transacylase gene (phaG) isolated from Pseudomonas putida in E. coli HB101 led to 587 mg L-1 extracellular production of 3-hydroxydecanoic acid (3HD) from fructose. The results demonstrated that HA can be produced by recombinant organisms directly without going through the PHA hydrolyzation process.