We report a theoretical study of highly excited O-3 in collisions with vibrationally cold OH. Special emphasis is placed on initial vibrational energies of O-3 between 9 and 21 kcal mol(-1). All calculations have employed the quasiclassical trajectory method and the realistic double many-body expansion potential energy surface for HO4((2)A). Many aspects of the title relaxation process are presented. The results indicate that it may not be ignorable in studying the stratospheric ozone budget.