N-Acylethanolamines (NAEs) constitute a family of endogenous bioactive lipids that includes arachidonoylethanolamide (anandamide), palmitoylethanolamide (PEA) and oleoylethanolamide (OEA). These lipids are formed from their respective N-acylated ethanolamine phospholipid (NAPE) precursor by the action of a phospholipase D enzyme (NAPE-PLD). Anandamide, OEA, and PEA are all bioactive lipids that may influence, amongst others: neuroinflammation, food intake, and oocyte implantation. Here we have synthesized a number of NAPE analogues with variation in the phosphoester structure. The NAPE analogues as well as selected phospholipids and beta-lactamase substrates were tested as potential modifiers of cloned human NAPE-PLD in an enzyme assay involving a (14)C-labeled diether-NAPE substrate. One hit was identified, namely 1,2-dihexanoyl-glycero-N-(3-(tetradecanoylamino)propyl)phosphoramidate (AHP-71B) which showed inhibitory activity and may serve as template for further structure-activity developments. Furthermore, it was found that NAPE-PLD was activated by phosphatidylethanolamine and inhibited by the beta-lactamase substrate nitrocefin.