Given that protein malnutrition induces structural, neurochemical and functional changes in the CNS, the present study aimed to investigate the effects of short-term early protein malnutrition on the behavior and reactivity to diazepam (DZ) in the elevated plus-maze test (EPM). Male Wistar rats (n=176) from well-nourished (16%-protein) or malnourished litters (6%-protein) were distributed in five different groups: W (well-nourished), M7 (malnourished for 7 days), M14 (malnourished for 14 days), M21 (malnourished for 21 days) and M28 (malnourished for 28 days) since birthday. EPM results showed that the longer the exposition to the deficient diet, the lower the anxiety of malnourished animals, a result similar to that produced by the treatment with DZ. This anxiolytic-like effect suggested that short-term malnutrition may affect neural and/or neurochemical systems believed to underlie behavioral expression in anxiogenic experimental situations.