We generalize the Wilemski-Fixman theory for reversible polymer cyclization to treat the kinetics of intrachain excimer-formation reactions. While most previous theories for intrachain reactions dealt with the end-to-end reaction case, we consider the general situation in which the reacting groups are located at any place on the chain backbone. Various aspects of the reaction kinetics, such as the effect of hydrodynamic interaction and the dependence of reaction rate on the positions of reacting groups as well as on the chain length, are investigated. (C) 2003 American Institute of Physics.