We have derived a general analytical expression for the high field recombination yield of a geminate radical pair (RP) that diffuses freely and is separated initially. The dependence of the recombination yield on the initial separation is obtained by a simple extention of the previously published Green's function method. An explicit expression is derived for diffusion controlled recombination through the singlet channel and it incorporates Zeeman and hyperfine interactions, intraradical relaxation (both transversal and longitudinal), and homogeneous scavenging. (C) 2002 Elsevier Science B.V. All rights reserved.