Background To observe the effects of valsartan on matrix metalloproteinase-2 (MMP-2) and tissue inhibitor of matrix metalloproteinase-2 (TIMP-2) in atrial fibrillation patients. Methods 30 patients with non-vavular atrial fibrillation(NVAF) as atrial fibrillation group (AF group) were randomly divided into two groups: 15 patients were in therapy group (valsartan 80 mg qd) and 15 patients were in control group. Plasma MMP-2 and TIMP-2 level between therapy and control group before and after treatment and 30 normal patients as normal group (SN group) were measured by ELISA. Results High levels of MMP-2 were observed in AF group comparing with normal group (P<0.01), and the level of TIMP-2 was significantly lower (P<0.01). There was no difference between therapy group and control group in MMP-2 and TIMP-2 before treatment. However,after three months treatment, MMP-2 in therapy group was significantly lower than control group(P<0.001). While in therapy group there was a significant difference before and after in MMP-2(P<0.01) and TIMP-2 (P<0.05). Conclusions There are high level of MMP-2 and lower TIMP-2 in NVAF patients. Valsartan might inhibit the process of non-vavular atrial fibrillation by down regulating of MMP-2 and up regulating of TIMP-2. Background To observe the effects of valsartan on matrix metalloproteinase-2 (MMP-2) and tissue inhibitor of matrix metalloproteinase-2 (TIMP-2) in atrial fibrillation patients. Methods 30 patients with non-vavular atrial fibrillation (NVAF) as atrial fibrillation Plasma (AF group) were randomly divided into two groups: 15 patients were in therapy group (valsartan 80 mg qd) and 15 patients were in control group. Plasma MMP-2 and TIMP-2 level between therapy and control group before and after treatment Results High levels of MMP-2 were observed in AF group comparing with normal group (P <0.01), and the level of TIMP-2 was significantly lower (P <0.01). There was no difference between therapy group and control group in MMP-2 and TIMP-2 before treatment. However, after three months treatment, MMP-2 in therapy group was significantly lower than control group (P <0.001). While in therapy group there was a significant differe Nals before and after in MMP-2 (P <0.01) and TIMP-2 (P <0.05). Conclusions There are high levels of MMP-2 and lower TIMP-2 in NVAF patients. Valsartan might inhibit the process of non-vavular atrial fibrillation by down regulating MMP-2 and up regulating TIMP-2.