This paper attempts to investigate the efficiency of typical curb inlet design used in Malaysia. Curb inlet is a common type of stormwater inlet of the urban drainage systems which functions to intercept excess stormwater on the street and convey them to another drainage system. The design (shape and type) of stormwater inlets used in a developing country like Malaysia, however might be considered as 'too simple' as compared to other developed countries. The choice of design might be heavily subjected to the aspect of easiness during construction. For a tropical country that receives a lot of rain throughout the year, this conventional design may eventually lead to street ponding. Thus, the effectiveness of these structures is then considered very crucial. Field investigation has been carried to study the actual performance of the curb inlet and its efficiency is reported. Results showed that the existing curb design would be efficient to intercept lower discharges because at higher discharges, the flow would be flowing downstream as bypass flows. Simple modification was proposed to the existing curb inlet by placing a 45? defelctor near the curb, which was found to be able to intercept 10 more flows to the inlets. © 2020 IOP Publishing Ltd. All rights reserved.