Pseudo-C-2-symmetric irreversible inhibitors of HIV-1 protease containing cis-epoxide were designed, synthesized, and kinetically characterized. Introduction of a Gly residue into P-1' of the inactivators yielded strong time-dependent irreversible ones with k(ina)/K-i ranging from 1.5x10(8) to 3.4x10(5) M(-1) min(-1).