This work aimed to study the T helper type 1/2 (Th1/Th2) cytokine profile in a co-infection murine model of Plasmodium chabaudi chabaudi and Leishmania infantum. Expression of interferon-gamma (IFN<FONT FACE=Symbol>-g</FONT>) and interleukin-4 (IL-4) was analyzed, in spleen and liver of C57BL/6 mice, by reverse transcriptase-polymerase chain reaction. High levels of IFN<FONT FACE=Symbol>-g</FONT> expression did not prevent the progression of Leishmania in co-infected mice and Leishmania infection did not interfere with the Th1/Th2 switch necessary for Plasmodium control. The presence of IL-4 at day 28 in co-infected mice, essential for Plasmodium elimination, was probably a key factor on the exacerbation of the Leishmania infection.