Southern chinch bug, Blissus insularis Barber, is a serious insect pest of St. Augustinegrass, Stenotaphrum secundatum (Walt.) Kuntze in Florida and other Gulf Coast states. Resistance to southern chinch bug has been identified in the St. Augustinegrass lines ‘FX-10’ and NUF-76. ‘Floratam’, once resistant to the southern chinch bug, is now susceptible. This research investigated the potential role of the plant oxidative enzymes, polyphenol oxidase, peroxidase, catalase and lipoxygenase in resistance and susceptibility to southern chinch bug. The levels of the above-mentioned oxidative enzymes were estimated from plant samples collected 1, 3, 5, and 8 d after southern chinch bug infestation and uninfested control plants. FX-10 and NUF-76 had significantly higher levels of peroxidase activity on 5 and 8 days after infestation in comparison to their respective controls. FX-10 had significantly higher levels of lipoxygenase on 3, 5 and 8 d after infestation. NUF-76 had significantly higher level of polyphenol oxidase on 5 and 8 d after infestation. Catalase activities did not differ significantly between infested and control plants of all the lines tested. Native gels stained for peroxidase indicated that one of four isozymes was induced on 5 and 8 d after infestation in FX-10. There were no differences in isozyme profiles between control and infested plants in NUF-76 and Floratam for polyphenol oxidase, catalase and lipoxygenase. The southern chinch bug resistance in FX-10 and NUF-76 was being correlated with, but not necessarily explained by, the higher levels of peroxidase, polyphenol oxidase and lipoxygenase in southern chinch bug-infested plants.