The temperature dependence of the magnetization (ac and dc) indicate that Sm1/3Sr2/3FeO3-d undergoes an antiferromagnetic transition at TN = 150 K. In low applied fields, the zero field cooled (ZFC) and field cooled (FC) magnetization below TN exhibit a hysteretic behavior. This behavior is suppressed by high applied field. The ac susceptibility for Sm1/3Sr2/3FeO2.95 shows that there is a clear frequency dependence developing below TN. The relusts of both ac and dc measurements suggest that the antiferromagnetic long-range order coexist with ferromagnetic correlations. Field-dependent resistivity versus temperature measurements reveal the existence of a magnetoresistance (MR) in the temperature below TN. The appearance of some ferromagnetic component within an antiferromagnetically ordered state may be responsible for the MR at low temperature.