Abstract: The aim of this study was comparing retention of cast post luted with two kinds of glass ionomer cement in different time intervals. In this in vitro experimental study 60 newly extracted maxillary canine teeth were chosen, the canals were prepared by step-back method and were filled with gutta percha and ZOE sealer. A 12 mm post space was prepared and the posts were made by conventional method using Duralay resin and cast with Supercast alloy. The teeth were divided into 6 random groups, 3 groups were cemented using Ariamix cement and the othacer 3 groups using GC Fuji 1 glass ionomer cement. The tension test was performed on each group, 20 min, 1 and 24 h after cementation and Instron machine was used for applying tension. Results were analyzed by two-way ANOVA and Tukey tests. The results revealed the fact that the tensile strength had a significant statistical difference between the 20 min, 1 and 24 h time intervals (p<0.001). There was no significant difference between two cements between time intervals. The best time interval was 24 h. This study revealed the fact that there was no significant difference between the retention of GC Fuji 1 cement and the Ariamix cement.