Background: High dose antipsychotic prescribing is common in psychiatric care, despite a lack of its benefit from research evidence. While several studies have explored the prevalence and factors associated with high dose antipsychotic prescribing, no such report has emanated from a developing country like Nigeria. Aim: The aims of this study were to determine the prevalence of high dose prescribing among inâpatients at a tertiary psychiatric hospital and to determine the pattern of antipsychotic drugs prescribed. Materials and Methods: An audit of inâpatients at a regional tertiary psychiatric facility was carried out. We examined case notes and conducted oral interviews where necessary, on all patients receiving antipsychotics using a proforma designed for the study. Results: The prevalence of high dose prescribing was 38% (65/171) using a prescribed daily dose/defined daily dose ratio of 1.5. The rate of antipsychotic polypharmacy was 7% (12/171). The atypical antipsychotic, olanzapine was the most commonly prescribed antipsychotic in monotherapy. Predictors of high dose prescribing were diagnoses (P = 0.04), polypharmacy (P = 0.04), a history of previous inâpatient care (P = 0.02), and use of anticholinergic drugs (P = 0.01). Conclusions: High dose prescribing was common among inâpatients audited. Further studies are needed to examine factors that promote “high dose” prescribing.