Objective: To compare three flowable composites (Esthet-X flow, Beautifil flow and Filtek Z350) with a hybrid composite (Z100), and two temporary filling materials (Cavit and IRM) as intra-orifice filling materials to prevent coronal microleakage. Methods: Root canal treatments were performed on 104 extracted human single-rooted premolars. Three millimetres of coronal gutta-percha was replaced by one of the six filling materials to seal the intra-orifice. After thermocycling (5°C to 55°C) for 750 cycles and immersion in Indian dye for 5 days, the teeth were evaluated for dye penetration along canal walls. The data were analysed with the Kruskal-Wallis test and the Mann-Whitney U test. Results: All of the three flowable composites sealed the intra-orifice of root canals as well as Z100, but significantly better than Cavit and IRM. There was no significant difference among the three flowable composites, or between Cavit and IRM. Conclusion: Flowable composites are ideal intra-orifice seals. Keywords: coronal leakage, flowable composite, intra-orifice seal