In order to investigate the effect of vitamin A (VA) on the secretion of IFN-γ and IL-4 in Mycoplasma Pneumoniae (MP)-induced A549 cells, A549 cells were co-cultured with MP for different time lengths and then the levels of IFN-γ and IL-4 in the cell culture supematants were detected before and after treatment with different concentrations of VA by using the enzyme-linked immunosorbent assay (ELISA). The results showed that the level of IFN-γ and IL-4 in the supatants of MP-induced A549 cells was much higher than that in non-induced cells (P<0.01). After application of VA, IL-4 level was not increased until the concentration of VA was up to 0.5 × 10-5 mol/L (P<0.01).However, with concentration of VA increased up to 1 × 10-4 mol/L, IL-4 was significantly suppressed (P<0.01). It was concluded that MP could induce the secretion of IFN-y and IL-4 in A549 cells. VA could inhibit the secretion of IFN-γ, and increase the IL-4 level in MP-induced A549 cells. However,high concentration of VA had an inhibitory effect on the secretion of IL-4 as well as on the IFN-γ.These data provided a theoretical basis for the application of VA in MP pneumonia in the clinical practice.