Crude lipoxygenase was obtained from a biomass culture of Fusarium oxysporum and partially purified by precipitation with ammonium sulphate at 20-80% of saturation. The enzyme exhibited two pH optima, a major activity at pH 10 and a minor one at pH 8. The apparent K-m values at pH 8.0 and 10.0 were calculated to be 3.28 x 10(-5) M and 3.55 x 10(-5) M respectively. At pH 8.0, lipoxygenase activity was inhibited by 31% at 20 mM potassium cyanide (KCN), exhibiting a non-competitive inhibitory effect. However, at pH 10.0, KCN had relatively little effect on enzyme activity. The addition of EDTA to the reaction medium activated the enzyme activity by 50.3% and 16.6% at pH 8.0 and 10.0, respectively. Substrate specificity of the enzyme was greatest towards linoleic acid, followed by linolenic acid, at both pH 8.0 and 10.0. In addition, the enzyme demonstrated higher activity towards the glycerol fatty acids at pH 10.0 compared to that at pH 8.0. Native polyacrylamide gel electrophoretograms of partially purified enzyme indicated the presence of one major and five minor band; of molecular weights of 67 000-140 000 Da.