Objective. We investigated the effect of the industrial frequency (50-60 Hz) magnetic field and nitrosamines on the behavioural parameters of the experimental animals. Materials and methods. In the experiments, we used the methods of automatic registration of locomotor activity which makes it possible to give the integral assessment of the innate forms of behaviour on the basis of the study of the motor activity of animals in the maze and the study of grooming (in our case, it is fur care) in rats.