Sesame seed (sesamum indicum L.) is one of the world's most important and oldest oilseed crops with a high level content of antioxidant known to human health. The antioxidant factors responsible for the stability of roasted sesame seeds is highly affected by the conditions of the roasting process. Survey of the roasting temperature and time effects on antioxidants and total phenolic content in Iranian sesame seeds was the aim of this investigation. Spectrophotometer methods based on folin-ciocalteau reagent for determination of total phenolic content (TPC) and Ferric Reducing Antioxidant Power assay (FRAP) technique for total antioxidant activity were used before and after different roasting processes. Some of 8 Iranian sesame seeds cultivares were studied (n = 160), including Branching Naz, Non Branching Naz, Dezful, Darab, Karaj, Moghan, Varamin and Black sesame. The range of FRAP values was between 0.301 ± 0.029 m M and 1.746 ± 0.083 m M in Moghan and Branching Naz seasem seed cultivares, respectively. The FRAP value increased from 0.974 ± 0.095 m M in unroasted Branching Naz as a control to 1.746 ± 0.083 m M after roasting in 200 ° C for 20min. Also TPCs increased significantly as the roasting temperature. The amount of TPC varied in different sesame cultivars from 20.109 ± 3.967 m M to 129.300 ± 3.493 m M in Varamin and Branching Naz sesame seed cultivares, respectively; also TPC increased from 70.953 ± 5.863 m M in unroasted Branching Naz sesame seed as a control to 129.300 ± 3.493 m M after roasting in 200 ° C for 20 min. Branching Naz seasem seed cultivare was at the highest level in total antioxidants and total phenolic contents in comparison to other samples; however Moghan and Varamin cultivares were at the lowest level in total antioxidants and total phenolic contents, respectively. The present study showed that Iranian sesame seed can be considered as a good source of natural antioxidant specially after roasting. The optimum temperature and time roasting to obtain the most antioxidants and total phenolic content was 200 ° C for 20 min.