Seismic evaluations of adjacent regular and irregular reinforced concrete buildings are commonly adopted in Ethiopian design philosophy; this evaluation is performed to proportion cross sectional elements of buildings like beam, column and slab. However, during design of adjacent buildings in seismic zone designers do not consider the minimum gap that should be provided between adjacent buildings, which may cause pounding effect during earth quake excitation. Several new buildings located in Ethiopian major towns are designed and constructed without considering the effect of existing buildings behavior in the surrounding under earth quake excitation. Different seismic zones may have different site conditions; in most cases a simple copy of building design from one seismic zone and site condition to another with or without modification of cross sectional element is a common practice in major towns of our country. However, in both cases there is no modification that is made on the gap between adjacent buildings. Even if the gap between adjacent buildings is sufficient in one seismic zone and site condition, it may not be sufficient for the other. The aim of this research was to assess the seismic gap requirement of adjacent buildings by considering all seismic zones and site conditions to prevent pounding. For evaluation purpose four independent buildings (two of them are regular and the other two are irregular) buildings were selected. The buildings were assumed to be constructed adjacently in three arrangement as a case study (i.e. regular vs. regular, irregular vs. regular and irregular vs. irregular) to compute a minimum gap required for preventing of pounding damage in different seismic zone and site conditions. Minimum gap was calculated by assuming zones verses site conditions as (zone 1 have site condition-A, zone 2 have site condition-B, zone 3 have site condition-C, zone 4 have site condition-D and zone 5 have site condition-E). All buildings were been analyzed by using the finite element software program, SAP2000, with response spectrum function. The analysis was conducted for elastic structures under different seismic zones.