Tests were conducted to determine the potential for high hydrostatic pressure (HPP) to control codling moth, Cydia pomonella (L.), and western cherry fruit fly, Rhagoletis indifferens Curran. Apples (Malus spp.) with codling moth larvae or eggs were treated at 24 and 72 h, respectively, after infestation at a series of pressures between 14,000 and 26,000 pounds per inch² (psi). Survivorship was determined the next day for larvae and after 10 d for eggs. Codling moth eggs were more tolerant of HPP treatment than larvae. Mortality of larvae was 97% at 22,000 psi, whereas mortality of eggs at this dose was 29% and not significantly different from the untreated controls. In a second study, no codling moth eggs hatched at any high pressure treatment between 30,000 and 80,000 psi, indicating these pressures were lethal. Various stages of western cherry fruit fly were treated at pressures from 10,000 to 45,000 psi, and survivorship was determined after 24 h. Eggs and third instars were more tolerant of HPP than the first and second instars. Mortality was 100% in western cherry fruit fly eggs and larvae at pressures ≥25,000 psi. Apple and sweet cherry quality after high pressure treatment was poor, but high pressure may have applications to control quarantine pests in other fruits.