The present study included evaluation of depth of cure according to ISO (4049:2009), hardness and marginal integrity (microleakage, dye penetration depth and marginal gap) of two different groups of resin-based composites. Group I: Filtek™Bulk Fill Posterior Restorative and group II: Filtek™Z350 XT Universal Restorative (control group).The study was done using cylindrical stainless steel specimens and sound extracted human molars.The cylindrical stainless steel specimens were prepared using stainless steel moulds and divided into two groups. Then filled with the bulk fill and conventional composites in accordance with the manufacturer’s instructions. The depth of cure was measured using electrical digital caliper and hardness of restorations measured using Vickers Hardness Test in each group. The sound extracted human molars were collected from National Institute of Diabetic and Endocrinology were divided into two groups, prepared and restored with bulk fill and conventional resin-based composites in accordance with the manufacturer’s instructions. The marginal microleakage was evaluated using stereomicroscope, dye penetration depth using digital microscope and marginal gap of restorations using scan electron microscope in each group.The depth of cure and microhardness of both groups was examined where Group (I) showed higher depth of cure than the group (II). The ratio of the hardness using Vickers Hardness Test showed that the group (I) is higher than group (II) between bottom and top surfaces of the specimens cured. The marginal integrity on sound extracted molars of both groups were examined where group (I) showed higher microleakage score and dye penetration depth than group (II).Regarding marginal gap assessment using scan electron microscope along the composite/enamel interfaces at mesial, distal and pulpal regions. There was no statistically significant difference between marginal gap distances in the two groups.Within the limitation of this study, we can concluded that the Filtek™Bulk Fill posterior resin-based composite can be cured ‘effectively’ to at least a 4-mm depth and all resin-based composite materials must be used according to manufactures’ instructions concerning the depth of cure and type of materials used.