In this study, the effects of pounding on seismic behavior of mid-risereinforced concrete (RC) adjacent buildings with insufficient separationdistance were investigated. 5, 8, 10, 13 and 15-storey RC building modelswere created to represent mid-rise buildings. The nonlinear behaviorproperties of these models are reflected by plastic hinges defined at thecolumn and beam ends. The buildings are modeled as a threedimensional (3D) column-beam frame system. Adjacent building modelsare derived, which are connected from floor to floor level using Kelvincontact elements. Total of 30 different adjacent building models werecreated with the use of buildings having different number of floors. The“0” m gaps reflect inadequate separation distance between adjacentbuildings while the “5” m gap is used for the reference building withoutcollision. In order to investigate the pounding effects between adjacentbuildings, 22 real acceleration records compatible with TBEC-2018were selected and scaled. Total of 660 3D nonlinear time historyanalyses were carried out and the roof displacement demands obtainedfrom these analyses were compared for collision and without collisioncases The outcomes of this study show that significant changes mayoccur in the building displacement demands due to the collision of themid-rise RC neighboring buildings with insufficient seismic gap. Basedon the findings obtained on significant number of adjacent buildingpairs with different period ratios, the displacement amplificationfactors (β) are proposed for the mid-rise RC buildings.