The manufacture of chemicals in microstructured reactors (MSR) has become recently a new branch of chemical reaction engineering focusing on process intensification and safety. MSR have an equivalent hydraulic diameter up to a few hundreds of micrometers and, therefore, provide high mass- and heat-transfer efficiency increasing the reactor performance drastically, compared to the conventional one. This article provides a comprehensive overview of the state of the art of the MSR applied for multiphase reactions. The reactions are classified based on the number of phases involved: fluid-fluid, fluid-solid, and three phase reactions. In the first part of the review, limitations of conventional reactors are discussed in brief. Furthermore, different types of MSR and their advantages with respect to their conventional counterparts are described. Particular attention is given to the identification of the parameters that control the flow pattern formed in microcapillaries regarding the mass-transfer efficiency. Case studies of various multiphase reactions carried out in MSR are discussed in detail.