The stiffness of structural elements (columns, beams, and slabs) significantly contributes to the overall stiffness of reinforced concrete (RC) high-rise buildings (H.R.B.s) subjected to earthquake. In order to investigate what percentage each type of element contributes to the overall performance of an H.R.B. under seismic load, the stiffness of each type of element is reduced by 10% to 90%. A time history analysis by SAP2000 was performed on thirteen 3D models of 12-story RC buildings in order to illustrate the contribution of column stiffness and column cross sections (rectangular or square), building floor plans (square or rectangular), beam stiffness and slab stiffness, on building resistance to an earthquake. The stiffness of the columns contributed more than the beams and slabs to the earthquake resistance of H.R.B.s. Rectangular cross-section columns must be properly oriented in order for H.R.B.s and slender buildings to attain the maximum resistance against earthquakes.