N-Acylethanolamines, including N-palmitoyl-ethanolamine (PEA), are hydrolyzed to the corresponding fatty acids and ethanolamine by fatty acid amide hydrolase (FAAH). Recently, N-acylethanolamine-hydrolyzing acid amidase (NAAA) was identified as being able to specifically hydrolyze PEA. In order to find selective and effective inhibitors of this enzyme, we synthesized and screened several amides, retroamides, esters, retroesters and carbamates of palmitic acid (1-21) and esters with C15 and C17 alkyl chains (22-27). Cyclopentylhexadecanoate (13) exhibited the highest inhibitory activity on NAAA (IC(50)=10.0 microM), without inhibiting FAAH up to 50 microM. Compound 13 may become a useful template to design new NAAA inhibitors.