Depression is a pathological state of mood and is considered as one of the major causes of disabilities. Thus, the prevention of depression and care for individuals with depression is important. In the present study, we examined whether a single oral dose of CBEX (chicken breast extract), or carnosine (one of the major components of CBEX) affects immobility time, an index of depressive-like behavior, in the forced swimming test in male Wistar rats. CBEX tended to (P=0.09) and carnosine significantly (P<0.05) decreased immobility time in the forced swimming test. In the hippocampus, both CBEX and carnosine significantly decreased 3-methoxy-4-hydroxyphenylglycol, a major metabolite of norepinephrine, indicating that CBEX and carnosine could reduce NE activity in the hippocampus in the forced swimming test. CBEX and carnosine did not affect total locomotive distance or rearing in the open field test, suggesting that the reductions of immobility time by both treatments in the forced swimming test were not merely due to the stimulation of general motor activity. Taken together, these results suggest that CBEX has an antidepressant-like effect, which may be due, in part, to the effect of carnosine.