Configuration-constrained potential energy surface calculations have been performed to investigate four-quasiparticle high- K configurations in neutron-deficient lead and polonium isotopes. A good agreement between the calculations and the experimental data has been found for the excitation energy of the observed K π = 19 − state in 188 Pb. Several lowly excited high- K states are predicted, and the large oblate deformation and low energy indicate high- K isomerism in these nuclei.