Objective To investigate the effects of dl-3-n-butylphthalide (NBP) on the oxidative damage and antioxidant capacity in patients with acute cerebral infarction.Methods Sixty-two patients with acute cerebral infarction were divided into NBP group (given NBP soft capsules) and control group (not given NBP soft capsules). Serum reactive oxygen species (ROS) and total antioxidant capacity (T-AOC) were measured by Fenton reaction and enzyme-linked immunosorbent assay and compared between the two groups.Results One week after treatment, the NBP group had a significantly lower serum ROS level (P<0.05) and a significantly higher serum T-AOC (P<0.05), as compared with the control group. The NBP group showed a significant increase in serum T-AOC after treatment (P<0.05). Two weeks after treatment, the NBP group had a significantly lower NHISS score than the control group (P<0.05).Conclusions NBP can protect nerve cells from oxidative damage through reducing ROS and increasing T-AOC, thus alleviating neurological deficit symptoms.