The activity of polyphenolooxidase (PPO) and β-glucosidase in the following fruits: strawberry, raspberry, red currant, black currant was estimated. From each kind of fruit three varieties were selected. Spectrophotometric methods were used to estimate the enzymatic activity. The substrates for the enzymatic reactions were catechol for PPO and p-nitrophenol-β-D-glucosidc for β-glucosidase. The influence of pH value and temperature on the activity of the enzymes and their thermal inactivation was also investigated. PPO activity was detected in the following varieties of strawberries: Senga-Sengana, Ducat. β-glucosidase activity in strawberries: Senga-Sengana, Ducat, Marmolada and in the following varieties of raspberry: Canby, Beskid, Seedling was studied. The optimal conditions for PPO were as follows: pH 4,5, temperature 45°C, and for β-glucosidase pH in the range of 5,0-5,5 and temperature 40°C to 50°C depending on the origin of the enzyme.