Objective To explore the effect of L-dopa on plasma homocysteine and folic acid in patients with Parkinsons’s disease (PD). Methods Twenty eight elderly PD patients and thirty normal subjects were enrolled in this group. The homocysteine, cobalamin and folate were examined in normal group and in PD group before treatment and after being treated with L-dopa for six months respec- Objective To explore the effect of L-dopa on plasma homocysteine ​​and folic acid in patients with Parkinsons’s disease (PD). Methods Twenty eight elderly PD patients and thirty normal subjects were enrolled in this group. The homocysteine, cobalamin and folate were examined in normal group and in PD group before treatment and after being treated with L-dopa for six months respec-