To explore the effect of anti-CD44 monoclonal antibody A3D8 on expression of transcription factor AP-1 in acute myeloid leukemia cells. After acute leukemia cell line HL-60 was treated by different concentrations of A3D8, the proliferation and cell cycle were detected by MTT and FCM respectively. The expressions of c-JUN and c-FOS at mRNA and protein level were detected by RT-PCR and Western Blot respectively. The proliferation of HL-60 was inhibited by A3D8. The A3D8 treatment increased the percentage of G0/G1 cells. The expressions of c-JUN at mRNA and protein level were both decreased in HL-60 cells treated with A3D8. The expressions of c-FOS at mRNA and protein level in rapamycin treatment groups showed no statistically significant difference as compared with that in control group. A3D8 can affect the activity of AP-1 through inhibiting the expressions of c-JUN at mRNA and protein level.