The choice of anesthetics for magnetic resonance imaging in rodents is a difficult and important task. Experiments carried out on small laboratory animals are analyzed in this review. Heart rate, mean arterial pressure, and respiratory rate measured during the experiment under anesthesia of various types are described. Since anesthetics affect the physiological state of animals, they indirectly influence the results of investigation. Therefore, prior to the start of experiment, a literary search has to be carried out in order to choose a method of anesthesia least affecting the parameters studied.