It is believed that free radical formation and subsequent oxidative damage in the form of lipid peroxidation may be a factor in the cerebral damage secondary to the ischaemia of a cerebrovascular accident (CVA). Total serum ascorbate and malondialdehyde (MDA) were measured in 45 patients with CVA on the day of admission to hospital (Time 0) and 48 hours later (Time 48 hours) and also in 45 age and sex matched controls. There was no statistical difference in total serum ascorbate between the control group (34.2 mumol/l +/- 3.1, mean +/- SEM) and the CVA patients at Time 0 (37.3 +/- 2.9) but there was a statistically significant decrease at Time 48 hours (22.7 +/- 2.0) (p < 0.001) in the CVA patients. With MDA there was no statistical difference between the patients at Time 0 (0.79 mumol/l +/- 0.06) and the control group (0.83 +/- 0.06) but there was a significant increase at Time 48 hours (1.65 +/- 0.08) (p < 0.001). These findings are in keeping with possible evidence of free radical damage in CVA.