Platelet-Activating Factor (PAF or 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine) is an important phospholipid mediator, which has diverse biological activities. PAF is synthesized and secreted by a variety of cells such as mast cells, monocytes, macrophages etc. Up-regulated PAF signaling can cause pathological inflammation and also has been found to be responsible for sepsis, shock, and traumatic injury. PAF-Acetylhydrolase (PAF-AH or 1-alkyl-2-acetylglycerophosphocholine esterase or Lipoprotein-associated Phospholipase A2 or Lp-PLA2) (EC 188.8.131.52) hydrolyzes PAF by removing acetyl group at the sn-2 position and converts PAF into biologically inactive form, lyso-PAF. PAF-AH has two forms: extracellular and intracellular that shares some similarities. In humans, PAF-AH deficiency leads to severe asthma, thus development of novel and specific inhibitors of PAF-AH is critical for therapeutic purposes. In PAF-AH Inhibitor Screening Kit, PAF-AH hydrolyzes the acetyl thioester bond at sn-2 position of substrate and free thiols are detected using DTNB. In the presence of PAF-AH inhibitor, the reaction is impeded. The PAF-AH Inhibitor Control is included to compare the efficacy of test inhibitors. The assay is high-throughput adaptable and can be finished in less than 1 hr.