Microstructure in organic semiconductor thin films has been regarded as the key factor determining the performance of the organic electronic devices. In the case of organic field effect transistors (OFETs) and organic photovoltaics (OPVs), the control of the surface characteristics of underlying substrates can govern the mesoscale and/or nanoscale ordering of the semiconductor assembled on them. Here, we present the effects of molecular orientation on the performance of OFETs and OPVs in various aspects. The correlation between molecular orientation of organic semiconductor thin film and the charge carrier mobility as well as bias stress stability of an OFET is presented. Also, the orientation-dependence of photovoltaic properties is discussed in OPVs.