We discuss the problem of computing the S‐matrix for scattering quarks and leptons from magnetic monopoles. We show that it is possible to make estimates of the relative strength of baryon‐number‐violating and baryon‐number‐conserving inclusive cross‐sections. We pay particular attention to the role of fermion masses and explore the way in which heavy fermion degrees of freedom ‘‘freeze out’’ of low‐energy scattering processes.