Aim: The aim of this study is to compare the effectiveness and safety of aripiprazole and amisulpiride as additional treatments to olanzapine in individuals with schizophrenia who have only partially responded to treatment. Material and methods: Total 110 patients were included and 100 patients were completed the study and were randomly distributed in Group I and Group II. Group I: Aripiprazole 10 mg once a day was administered as add on therapy for 6 weeks to all patients in Group I (n=54) who were already receiving tablet olanzapine 20 mg. Group II: Amisulpiride 100 mg once a day was administered as add on therapy for 6 weeks to all patients in Group II (n=56) who were already receiving tablet olanzapine 20 mg. Assessments of all the patients were done for improvement in symptoms and presence of adverse effect after 3rd& 6th week of therapy. Results: The average differences in PANSS score from the first measurement were statistically significant (p = 0.001) at the 3rd and 6th week for both groups. The mean PANSS score in Group I increased by 28% from baseline on the 3rd week of therapy and by 42% on the 6th week. In Group II, the mean PANSS score increased by 20% on the 3rd week and by 36% on the 6th week. Although there was a greater clinical improvement in group I on the 3rd and 6th week, the difference was not statistically significant (P=0.15 and P=0.19, respectively) compared to group II. The frequency of adverse effects is determined by calculating the percentage of patients in a certain group that had at least one treatment emergent adverse medication reaction. The incidence of negative side effects in the 6th week in Group I was 36%. The predominant adverse impact seen was somnolence in 12% of patients. In Group II (olanzapine plus amisulpiride), the frequency of adverse effects at 6th week was 48%.The most common adverse effect noticed was somnolence which was seen in 14% patients. Conclusion: The research clearly demonstrates that combining aripiprazole or amisulpride with olanzapine resulted in significant clinical improvement in individuals with schizophrenia who had only partly improved with olanzapine alone. However, aripiprazole was shown to be more effective and safer when used as an additional medication with olanzapine, compared to amisulpride.