A field study was carried out to investigate the effect of induced high temperature stress on the activity of superoxide dismutase (SOD), catalase (CAT), peroxidase (POX), and proline content, membrane stability index and lipid peroxidation in terms of malondialdehyde content in six rice genotypes, viz., IET 21404, IET 21577, IET 21411, IET 21405, IET 21415 and KRH 2. Flag leaves of rice at flowering stage were used for the analysis of enzyme activities. Elevated temperature significantly increased the activity of SOD (46.05 %), POX (66.00 %), and CAT (41.83 %). This increase was associated with increase in lipid peroxidation and decrease in membrane stability. In general IET 21404 and IET 21577 showed relatively higher SOD, CAT and POX activity as compared to IET 21411, IET 21405, IET 21415 and KRH 2. Significant increase in proline content, malondialdehyde content and decrease in membrane stability index were observed in all the genotypes of rice at anthesis.