Macroporous copolymer particles have a broad range of applications such as ion exchange resins and sorbents, catalyst supports, and carriers of biologically active species. Many of these applications require precise control of the dimensions of microbeads in the range from 50 to 100 mu m and predetermined size of pores. IN This paper reports semicontinuous photoinitiated microfluidic synthesis of macroporous polymer particles with the designated dimensions and a range of internal structures. Comparison with microspheres synthesized by conventional suspension polymerization shows,that microfluidic synthesis provides better control over the porous structure of the microbeads.