Nanoparticles have been aresearchfocusformorethantwodecades. The advent of microfluidic technology provides alternative strategies for the synthesis of nanoparticles in reactors having a micrometer length scale. The integration of nanoparticleand microreactor technologies delivers enormous opportunity and impetus for the further development of novel materials and reactors. In this article, recent achievements in the synthesis of nanoparticles in microfluidic reactors are reviewed. A variety of strategies for synthesizing nanoparticles are presented and compared, including continuous flow, gas-liquid segmented flow and droplet-based microreactors. Different categories of nanoparticles manufactured in microreactors are summarized to highlight the wide applicationofmicrofluidic systems in the development of novel nanomaterials. The control of nanoparticle synthesis is also briefly discussed. (C) 2010 Elsevier Ltd. All rights reserved.