This article describes a spin coating process for making micropatterns with curved surfaces. Liquid photoresist was used to compensate etched profile of microchannels on a silicon substrate. Due to the surface tension of liquid, curved surfaces or slopes could be obtained by coating photoresist on the rectangular microstructures. The results depend on properties of photoresist, geometry of microstructures and coating conditions. In this study, revolution speed of spin coater is a major coating condition. And tests were done for various microchannels with different size and direction. After coating the photoresist layer, it was heated on a hot plate so that its shape could be fixed. The final profiles of curved structures were examined with a polymer replica which was applied on the photoresist surface. The profile was controlled by changing revolution speed in spin coating process, but it also depended on the size and direction of microchannels. POLYM. ENG. SCI., 2012. (c) 2011 Society of Plastics Engineers