Neurotoxicity of first-generation antipsychotics (FGAs) may be involved in lipid peroxidation, which is the pathogenesis of extrapyramidal symptoms, including tardive dyskinesia (TD). Blood samples at day 0, 7, and 21 drawn from patients taking antipsychotics were analyzed for malondialdehyde (MDA) in plasma, a marker of lipid peroxidation, by high-performance liquid chromatography. Of 115 patients enrolled, 92 patients completed the study. Most MDA levels were within normal ranges (<1.0 μmol/liter). Malondialdehyde levels in patients receiving clozapine (p=0.002), quetiapine (p=0.003), amisulpride (p=0.008), and risperidone (p=0.008) were significantly lower than within the first generation antipsychotic group. The authors conclude that lipid peroxidation is significantly higher in treatment with FGAs.