Objective: To evaluate the impact of olanzapine, alone or in combination with other atypical antipsychotics (AAPs), on metabolic changes, in psychotic patients at Sultan Qaboos University Hospital (SQUH), Muscat, Oman. Methods: This is a retrospective cohort study, in patients attending psychiatry clinics at SQUH, Muscat, Oman, between 1st January 2019 and 31st December 2019, and prescribed olanzapine, alone or in combination with other AAPs. Patients were followed up retrospectively from the start date till April 2021. The metabolic components included body weight, body mass index (BMI), total cholesterol, low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), triglycerides, glucose, hemoglobin A1c, (HbA1c), systolic blood pressure (BP) and diastolic BP. Therapeutic goal attainments were evaluated as per the Task Force for the Management of Dyslipidaemias of the European Society of Cardiology (ESC) and European Atherosclerosis Society (EAS) in 2019. Results: The study enrolled a total of 253 patients (with a mean age of 40±17 years and 69% (n=174) were females) of which 78% (n=197) were on olanzapine alone while 22% (n=56) were on olanzapine in combination with other AAPs. After excluding patients with diabetes mellitus, hypertension and dyslipidemia (n=195), AAPs were associated with significant increases in body weight (+8.6; 95% confidence interval (CI): 7.0-10.2 kg; p<0.001), BMI (+3.4; 95% CI: 2.7-4.0 kg/m2; p<0.001), total cholesterol (+0.4; 95% CI: 0.3-0.5 mmol/L; p<0.001), LDL-C (+0.3; 95% CI: 0.2-0.4 mmol/L; p<0.001), triglycerides (+0.3; 95% CI: 0.2-0.4 mmol/L; p<0.001), glucose (+0.4; 95% CI: 0.3-0.6 mmol/L; p<0.001), HbA1c (+0.2; 95% CI: 0.1-0.3%; p<0.001), systolic BP (+9; 95% CI: 7-11 mmHg; p<0.001) and diastolic BP (+3; 95% CI: 2-5 mmHg; p<0.001). No changes in HDL-C were observed (p=0.981). Therapeutic goal attainments for the lipid components were 38% (n=97), 61% (n=154), and 71% (n=180) for LDL-C, non-HDL-C, and triglycerides levels, respectively. A total of 59% (n=150) of the patients were at their BP goal while only 28% (n=71) had normal optimum body weight. HbA1c was at goal (<7%) in 96% (n=236) of the cohort. Conclusions: Olanzapine was associated with significant increases in metabolic components. A significant proportion of patients were not at their therapeutic targets.