The authors investigated exploratory behavior patterns of white rats under normal and experimental dietary conditions. Two (2) experimental groups were studied; one received a low level protein diet ad libitum, the other a high protein diet with restricted portions during 47 days. After this period the rats received a fiftheen days free protein diet, and recovered, afterwards, with meat or casein diet. Rats showed abnormalities of exploratory behavior in all experimental periods and the authors concluded that it could be related to dietary treatment.