The latest version of the International Center for Theoretical Physics (ICTP)rnRegional climate model version 4 (RegCM4) is used to study the inrnuences ofrn ve di erent Lateral Boundary Schemes (LBSs) on the simulated rainfall forrna period of 20 years. The rainfall from RegCM4 simulations under the vernLBSs are compared with the observed rainfall in Climate Research Unit (CRU)rnand Global Precipitation Climatology Project (GPCP) dataset. The spatialrndomain encompasses the whole continental Africa and includes the Indianrnand south Atlantic ocean basins to capture the major circulation featuresrndominating eastern Africa. The comparison of the model results of rainfallrnwith observations from CRU and GPCP indicates a wet bias over east Africanrnhighlands while a dry bias is observed over the east African lowlands for allrncases. The mean annual cycle of rainfall is well captured over east Africanrnsubregions for each LBSs. The mean annual cycle also indicates that somernpart of the east African countries are characterized by bimodal rainfall trendrnwhich is well captured by all simulations. The observed precipitation inter-rnannual variability is well reproduced by the regional model over most regions,rnalthough RegCM4 simulations show some de ciencies. It is found that thernuse of sponge as well as the exponential LBSs reproduces realistic rainfall asrnexhibited by good agreement with GPCP and CRU rainfall