Abstract
A brief review is given of exotic atoms and the effect on their energy levels of the strong interaction. This is followed by a more detailed review of the special case of kaonic hydrogen and the discrepancy between the scattering and the bound-state experiments which has been unexplained for well over a decade. There are comments on the difficulties encountered in the experiments and possible reasons are given why the published results may be spurious. The single-channel optical model potential of Law et al. was used for a large number of searches and a number of parameter sets found which gave perfect fits to the scattering length and shift and width. Their work was extended to include the finite size of the proton and excellent fits found but the resulting potentials were too strong to be plausible. An exact relativistic calculation is described in which the integrals are evaluated in closed form and the importance of relativistic effects investigated. This could form the basis of a coupled-channels calculation which would be much more reliable than the numerical method of Schnick and Landau.