SUMMARY— The effect of radio-frequency (R-F) energy at 60 MHz on peroxidase, polyphenolase, pectinesterase, catalase and alpha-amylase activity was determined in water solutions of purified enzymes as well as in apple juice, milk and sweet potato extract. The apparatus used consisted of an R-F generator coupled to an evaporator and condenser. Temperature was kept constant at a desired level by evaporating water from the system. Results showed that while the enzymes were partially or totally inactivated by heat at 70°C. or 65°C (149°F) in the instance of milk, exposure to R-F energy at 20°C caused essentially no loss of enzyme activity. Within the limits of the experimental conditions, pH and enzyme concentration were not factors in relation to lack of effect of R-F energy on enzymes. Overall, the results indicate that per se, R-F energy at 60 MHz does not have any significant effect on the enzymes studied, aside from that caused by the heat effects of R-F energy.