In an earlier cross-sectional study, we reported antipsychotic-naive schizophrenia patients to have significantly elevated β2-microglobulin (β2M) level suggestive of its potential association with the pathogenesis of schizophrenia. In this study, we present the follow-up analyses of β2M in 31 patients from the previous study who were re-assessed after 92.1±7.2 days of antipsychotic treatment. Compared to baseline, there was a further significant elevation of β2M in schizophrenia patients following treatment, especially in those who were treated with risperidone. Also, there was a significant negative correlation between β2M level and total psychopathology score during follow-up in risperidone group. The study findings extend further support the role for β2M in the pathogenesis of schizophrenia strengthening the case for immune dysregulation. Moreover, the observations suggest the possibility that the mechanism of action of antipsychotics might involve alteration of immune parameters.