Abstract: The mountains and highlands in the tropical areas receive more rainfall than the nearby lowlands, in highland areas at least on their windward sides. It is well known that a large part of the heavy rain received on the western side of Sri Lanka is induced by the topographic barriers known as the Central Highland (CH). The objective of this study was to examine whether these orographic rainfall profiles more or less agree with the global figures of the orographic rainfall in the tropical mountains. The orographic effect of the western side of the CH of Sri Lanka has been studied with reference to the annual average rainfall and Southwest Monsoon rainfall using data from 1959-2002. Monthly rainfall data were obtained from the Department of Meteorology in Colombo, Agro-Meteorology Unit, Department of Agriculture, Peradeniya and Nakagawa et. al, (1995). The study area consists of nine representative locations of both sides of the CH elevation ranging from 2 to 1667 meters. These locations are Colombo, Kalutara PWD, Ratnapura, Abergeldie Group, Annifield Estate and Sandirigama, which lie on the western sides and Badulla, Wewessa and Dyraaba lying on the leeward side of the CH.