A coupled assay of phospholipase-A2 and lipoxygenase that especially can be applied to the determination of phospholipase-A2-inhibition is described. A partialsynthetic dilinolenoylglycerophosphocholine is used as substrate in the form of mixed micelles with Twenn-20. Pentadienoic fatty acids primarily produced by venom phospholipase-A2 are peroxydized in a second step quantitatively. Diminution in oxygen content is registrated by an oxygen sensitive electrode and the reaction process is plotted continuously. The usefulness of this assay in the screening of inhibitors and disturbing influences are discussed.