Background:Most of the studies have looked into the effect of typical antipsychotics on speech secondary to tardive dyskinesia.Aims:This study was aimed to explore the factors predicting the effect of atypical antipsychotic medications on the production of speech.Materials and Methods:One hundred and forty patients on stable regimen of three or more months on risperidone (92), olanzapine (28), aripiprazole (14), and clozapine (6) were recruited for the study. Speech was assessed by maximum phonation duration task, s/z ratio, diadochokinetic task, acoustic analysis and Frenchay Dysarthria Assessment (FDA). Extrapyramidal symptoms (EPS) were assessed by Simpson Angus scale.Statistical Analysis:Spearman correlation analysis was carried out to find the association between speech parameters and continuous variables. Effect of EPS, duration and dose of antipsychotic treatment on speech parameters was compared using Mann-Whitney test.Results:The risperidone group differ from other antipsychotics groups significantly in s/z ratio (0.07), FDA-total (0.23) and FDA-reflex (0.25). People who took antipsychotic for more than 2 years had lower score of FDA-palate (P = 0.042), and FDA-respiratory (P = 0.04) and higher values in noise-harmonic ratio (P = 0.011) and maximum /fundamental frequency (MFF) for males (P = 0.02). Effect of EPS was seen on MFF for males (spearman correlation coefficient = 0.34) and on almost all sections of FDA (spearman correlation coefficients = -0.2 to -0.33).Conclusion:Both duration of use and propensity of atypical antipsychotics to cause EPS can influence the speech performance of the patients. This information can be useful, particularly in people with the requirement of high quality speech.