The effect of non-homogeneous magnetic fields of a field intensity of 15,000-28,000 Gauss on the catalytic activity of the enzymes catalase and glutamate dehydrogenase was investigated. A difference in catalase activity could not be established by measurements with and without a magnetic field. Glutamate dehydrogenase activity was 12-15% lower than without a magnetic field. Conditions favoring magneto-catalytic phenomena are discussed.