The polymerase chain reaction (PCR) method is widely used for the reproduction and amplification of specific DNA segments in vitro, and a novel PCR method using nanomaterials such as gold nanoparticles has recently been reported. This paper reports on the regulation of PCR efficiency with superparamagnetic nanoparticles in a rotating magnetic field. The level of efficiency was successfully regulated in a rotating magnetic field by the authors, and decreased with increasing frequency of the field. The results obtained show that simply controlling the structure and dynamics of magnetic nanoparticle clusters in a rotating magnetic field can regulate PCR efficiency. (c) 2011 Elsevier B.V. All rights reserved.