Iatrogenic or drug induced disease is of great clinical significance in therapeutics. Treatment with antidepressants like selective serotonin reuptake inhibitors (SSRIs) and antipsychotics reveal Bruxism (excessive grinding and clenching of the teeth) as such type of iatrogenic disease, however it is rarely found with atypical antipsychotic drugs like Olanzapine. A 50-year male patient, suffering from schizophrenia was under regular antipsychotic medication receiving Tab. Olanzapine 5 mg O.D., Tab. Clonazepam 0.5 mg O.D. regularly for past 25 years. Recently he gradually developed excessive grinding and clenching of teeth despite of any dental and ENT clinical complications. Biochemical and hematological tests also showed normal result. On admission with the complication of bruxism, tab. Olanzapine dose was reduced to 2.5 mg OD, however even after dose reduction there was not much improvement in bruxism. On the 4th day of the admission tab. Olanzapine has been substituted with tab. Clozapine 50 mg TDS. After 1 week of withdrawal of Olanzapine there was no complain of bruxism and he was discharged. On follow up after 1month the complication was occasional. Causality assessment revealed a probable relation between Olanzapine and Bruxism. Though among the atypical neuroleptics, extrapyramidal side effects are thought to be less common with olanzapine, but it may cause fatal consequences. Therefore, this case study and proper investigation may be helpful in designing the treatment strategy in more effective way and also aware all the healthcare professionals to monitor the patients on neuroleptics.