Objective: To investigate the presence of voids in bulk fill flowable composites. Methods: This study investigated two well-known bulk-fill flowable composites, Smart Dentin Replacement (SDR) (Dentsply/Caulk, Milford, Germany) and Filtek bulk fill flowable (FBF) (3M ESPE, Minnesota, USA). Three ampules of each material were randomly selected. The ampules were subjected to 3D Micro-CT (General Electric Phoenix V|Tome|X L240) reconstruction in order to assess the presence of any voids within the ampules. results: Voids were present in all the ampules. The total void percentage for each group of three ampules was found to be SDR : 1.147 % and FBF : 0.0424 %. There was a significant difference between the volume of voids for SDR and FBF, p-value=0.003924. conclusion: Voids were found in the randomly selected samples of bulk-fill flowable composites. This is undesirable and manufacturers should be urged to ensure that no voids are present, or at least are minimized in the ampules of material.