Thisisaninvitrostudyforevaluationofsomephysico-mechanicalpropertiesfor bulk fill and conventional nano hybrid compositeresins. Materialsandmethods:twotypesofcompositeresins.TetricevoCerambulkfill and conventional nano hybrid composite (Z250XT) used for measuring polymerizationshrinkage andhardness.A totalof 120specimenswerepreparedand equally dividedintotwomaingroupsaccordingtotest type. Eachmaingroupwere subdividedintotwomainsubgroupsaccording tothecompositeresinused. Thetwo mainsubgroupsweresubdividedintothreeclassaccording tostoragetimeindistilled water for 24hours,7daysand30days.The polymerizationshrinkage wasmeasured by computer vision system. Surface microhardness was measured by Vickers hardnesstester. Statisticalevaluationwas performed usingtwo-wayanalysis of varianceANOVA and tukey's test (p<0.05). Result:thepolymerizationshrinkageofTetricevoCerambulkfill islowered comparedtoconventionalnanohybridcompositeresin.Also,TetricevoCerambulk fillhashigher hardness thanconventional nano hybridcompositeresin. Also,storage time had significant effect(30days>7days>24 hours). Conclusion:bulkfilcomposite hasgoodphysicalandmechanical propertiesthan conventionalnanohybridcompositeresin.Waterstoragehassignificanteffecton properties ofcompositeresin.