Performance-based building engineering requires the synchronization of performances between non-structural and structural components. However, non-structural components are not generally taken into account in structural modelling. In this study, it is aimed to examine the seismic damage effects of non-structural components (NCs) on earthquake performance of RC buildings. For this purpose, 5 multi-story RC building collapsed in a strong earthquake is modelled as three dimensional (3D) using SAP2000 software. Brick, bookcase, bedroom, armchair, washing machine, dish washer, refrigerator is selected as NC in 3D analyses. NCs are modelled as anchored and unanchored to RC building and these NCs are modelled in the RC building taking into account UBC 2018, IBC 2018, ASCE/SI 7-30 code, New Zealand code, and Eurocode 8 code. Considering these standards for anchored / non-anchored / non-NC situations, earthquake analyses are performed separately for far fault and near fault. According to 3D nonlinear seismic analyses, it is clearly seen that NCs strongly affect earthquake behaviour of RC buildings. Besides, it is strongly recommended that non-structural elements should not be ignored while modelling a RC building. Then, it is understood that anchoring or not anchoring non-structural elements to RC structures seriously changes nonlinear seismic behaviour of these structures.