The PHENIX Collaboration at the Relativistic Heavy Ion Collider has measured open-heavy-flavor production in Cu+Cu collisions at sNN=200 GeV through the measurement of electrons at midrapidity that originate from semileptonic decays of charm and bottom hadrons. In peripheral Cu+Cu collisions an enhanced production of electrons is observed relative to p+p collisions scaled by the number of binary collisions. In the transverse momentum range from 1 to 5 GeV/c the nuclear modification factor is RAA∼1.4. As the system size increases to more central Cu+Cu collisions, the enhancement gradually disappears and turns into a suppression. For pT>3 GeV/c, the suppression reaches RAA∼0.8 in the most central collisions. The pT and centrality dependence of RAA in Cu+Cu collisions agree quantitatively with RAA in d+Au and Au+Au collisions, if compared at a similar number of participating nucleons 〈Npart〉.