Lactating rats were fed either the commercial diet (CO) or the low protein diet which induced symptoms of protein - energy deprivation (PD). They were housed in cages either individually (IH) together with eight offspring or in a large community cage (COM) shared by six dams and 48 youngs. After weaning all rats lived in cages by 4-5 animals. The PD terminated at the age of 49 days. Behaviour was tested on the 10th, 42nd and 150 th days of life. Body weight was recorded during nursing period both in dams and pups, after weaning in male rats. The low protein diet affected both body weight and maternal behaviour of the dams. In PD + IH pups growth as well as behavioural development was retarded. Behavioural alterations persisted even after the PD had been treated. The COM housing improved the body weight in the PD + COM dams, behaviour of both the PD + COM dams ond the pups was less affected than of the PD + IH group. The effect of the early housing was long lasting, manifested itself in elevated exploratory activity and in the decreased emotional responses in both the PD + COM and the CO + COM groups at the age of 42 and 150 days.