Mr G, a 62-year-old married man, retired electrician by occupation was brought by his family members with complaints of hearing of voices over the past 10 years. There was no relevant medical history or family history of mental illness. Detailed exploration of history revealed an illness of insidious onset with a continuous and progressive course which was precipitated by interpersonal problems with office colleagues. Following which initially, the patient started to harbour strong fixed false beliefs that his colleagues wanted to defame him with subsequent anger-outbursts, agitation and suspiciousness towards them. Later on, after few months, he even started to hear voices of his office colleagues in clear consciousness discussing him and commenting on his actions using derogatory language. Due to these events, there was significant socio-occupational dysfunction. He was treated with risperidone (2-4 mg/day) with good compliance for a period of 6 months with which there was about 60% improvement but later because of non-compliance and restarting of risperidone he did not show any response. Detailed general physical and systemic examination did not reveal any abnormality and mental status examination was suggestive of auditory hallucinations:third person discussing type, delusions of persecution and reference, low mood and suicidal ideations secondary to psychotic symptoms with absence of insight and intact cognitive functions (Mini mental state examination:28/30). A diagnosis of paranoid schizophrenia as per ICD-10 was considered. After all essential routine haematological (complete blood count) and biochemical investigations (serum electrolytes, liver function tests, lipid profile, renal function tests, serum vitamin B12 and folate), all of which came out to be normal, he was started with Olanzapine 5 mg which was gradually increased to 15 mg over a period of 3 weeks (5 mg increment in dose per week). There was reduction in psychotic symptoms by 40%-50% but on subsequent follow-ups, after 6 weeks of starting Olanzapine, the patient complained of excessive fatigability. On repeat investigations, there was evidence of total leucocyte count of 2600/cumm (baseline:9400/cumm) and total platelet count of 45 000/cumm (baseline:130 000/cumm) without any evidence/history of fever and symptoms suggestive of any local or systemic infection and intake of any other medications. Haematology consultation and detailed autoimmune workup to rule out other possible aetiologies (hepatosplenomegaly, autoimmune antinuclear antibodies and antineutrophil cytoplasmic antibodies) were found to be negative. Following this, a possibility of Olanzapine induced leucopaenia and thrombocytopaenia was considered and the drug was stopped. The patient was admitted for inpatient serial monitoring of haematological parameters and after stopping of Olanzapine, serial monitoring revealed an increase in total leucocyte count (8900/cumm) and total platelet count back to normal range (156 000/cumm) within a week. Later on, he was started on aripiprazole 2.5 mg with a very slow hiking of dosage (2.5 mg/fortnightly) along with monitoring of haematological parameters and psychopathology. At 10 mg of aripiprazole after a period of 30 days, the patient showed significant improvement in mood and psychotic symptoms by around 75% and his haematological parameters continued to remain stable over the next 4-month follow-up period. The prognosis of the patient was good and there was no relapse of any haematological abnormalities.