The changes of plasma corticosterone and prolactin levels have been studied in rats after single, repeated or cross exposition to the moderate Stressors : handling and transfer. The diminution of corticosterone and prolactin response has been found after repeated handling, but not after repeated transfer. The corticosterone level was significantly elevated in both cross-transfer and cross-handling groups and plasma prolactin level was significantly higher in the cross-handling animals. Both hormones manifested a parallel reaction to stress, prolactin being more difficult to obtain diminution of the reaction, corticosterone being more adaptable to repeated stress. It is concluded that the cross-adaptation between used stressful stimuli apparently could not be demonstraded, but, in contrast, the organism adapted to one stimulus possesses a greater corticosterone and prolactin reaction when being exposed to the new stimuli.