Aim To investigate the effect of peroxisome proliferator-activated receptor γ(PPARγ) ligands on inflammatory cytokine and matrix metalloproteinase(MMP) secretion by macrophages and foam cell. Methods THP-1 monocytes were differentiated to macrophages in vitro by addition of PMA,and then induced into foam cell by oxidized low density lipoprotein(ox-LDL).Semi-quantitative reverse transcription polymerase chain reaction(RT-PCR) was performed to detect the expression of PPARγ.Macrophage CD40 protein expression was detected by Western blot.Interleukin 6(IL-6),tumor necrosis factor α(TNF-α) and MMP-9 secretion in foam cell culture medium was measured by enzyme-linked immunosorbent assay(ELISA).MMP-9 activities were determined by gelatin zymography. Results Macrophages expressed PPARγ and treatment with ox-LDL did not affect the expression.PPARγ ligand pioglitazone greatly inhibited macrophage expression of CD40 in a dose-dependent manner.Moreover,pioglitazone significantly inhibited the secretion of IL-6,TNF-α and MMP-9 by foam cell as well as the activity of MMP9(p<0.05),although it had no effect on MMP-2 secretion or activity. Conclusions peroxisome proliferator-activated receptor γ ligands significantly inhibited the secretion of several inflammatory molecules by macrophages/foam cell which were closely related to atherosclerotic (As) plaque development and plaque instability.Thus,PPARγ ligands may have potential advantages in As therapy.