Introduction: Antipsychotics may in different ways affect the oxidative stress measured by plasma lipid peroxidation. Probably some of them may intensify the oxidative balance disturbances occurring in schizophrenia. The effects of amisulpride and risperidone on redox processes are not known sufficiently yet. Aim of the study: Establishment of the effects of amisulpride and risperidone on human plasma lipid peroxidation measured by determination of the level of thiobarbituric acid-reactive substances (TBARS), in vitro. Material and methods: Blood for the studies was collected from healthy volunteers (aged 24-26 years) for ACD solution. Active substances of the examined drugs were dissolved in 0.01% dimethylsulfoxide (DMSO) to the final concentrations (of amisulpride 578 ng/ml and risperidone 64 ng/ml) and incubated with plasma for 1 and 24 hours at 37ºC. For each experiment the control samples of plasma with DMSO (without the drug) were performed. The lipid peroxidation level was measured in plasma by determining the TBARS concentration, using the spectrophotometric method (acc. to Rice-Evans, 1991). The results were analysed using the following statistical methods: the paired Student t-test and ANOVA II variance analysis and NIR test (StatSoft Inc., Statistica v. 6.0). Results: The ANOVA II variance analysis indicated significant differences in the effects of both drugs on TBARS level (F=4.26; df=2, p<0.05). With reference to control samples, amisulpride after 24 hours’ incubation with plasma caused a significant decrease in TBARS concentration (p<0.003), whereas risperidone – an increase in TBARS concentration by 14% (p>0.05). Conclusion: Amisulpride and risperidone in concentrations corresponding to doses recommended for treatment of acute episode of schizophrenia do not induce oxidative stress measured by lipid peroxidation. Unlike risperidone, amisulpride exhibits antioxidative effects.