A fourth-order perturbation theory calculation is made of baryon-baryon forces arising from the exchange of K mesons. Results are compared with experiment. If it is assumed that the K meson is coupled equally to all baryons, while the pion is coupled weakly to hyperons, it is found (for either scalar or pseudoscalar K) that the Λ-nucleon potential does not have the right spin dependence to give agreement with binding energies in hyperfragments. If, on the other hand, it is assumed that the pion is coupled with the same strength to all baryons, then one can obtain agreement with experiment if the baryon-baryon potentials arising from K exchange are small. This is not inconsistent with fairly large K coupling constants. These conclusions, however, become tenuous if K-baryon couplings are as strong as the π-nucleon coupling (for example, if the PS coupling constants are comparable).