Aim: We investigated clinical and metabolic variables of obesity and body mass index (BMI) among two groups of unmedicated schizophrenia patients from the Croatian population: antipsychotic-naïve first-episode patients and nonadherent chronic patients. Patients and methods: Information about medication nonadherence was obtained via self-report. Patients were classified as obese with BMI > 30, and non-obese, those who were overweight (BMI: 25 – 30), or those having a normal weight (BMI: < 25). Results: Compared with non-obese patients with first-episode schizophrenia, obese with first-episode schizophrenia were older at disease onset; scored lower for depression factor; had higher ratios for LDL cholesterol (low density lipoprotein cholesterol, LDL-c)/HDL cholesterol (high density lipoprotein cholesterol, HDL-c) and triglycerides/HDL-c, and higher glucose levels (P < 0,05). Compared with non-obese nonadherent chronic individuals, obese nonadherent chronic individuals manifested higher number of psychotic episodes; scored lower for positive factor and experienced lower HDL-c levels (P < 0,05). Among first-episode schizophrenia individuals, BMI positively correlates with triglyceride and glucose levels, ratios for LDL-c/HDL-c and triglycerides/HDL-c, and negatively with HDL-c levels (P < 0,05). Among nonadherent chronic individuals, BMI positively correlates with number of psychotic episodes and negatively with Positive and Negative Syndrome Scale (PANSS) general psychopathology scores, PANSS total symptom scores, cognitive factor and HDL-c levels (P < 0,05). Multiple regression analysis indicated that the contribution of obesity to investigated variables ranged from ~3.1% to 9%, while the contribution of BMI ranged from ~4.5% to 29.4%. Conclusion: Obesity and higher BMI protect against clinical psychopathology among chronic patients. Obesity delays disease onset among first-episode schizophrenia patients. Higher BMI is a risk factor for number of psychotic episodes and lower HDL-c levels among chronic patients, while among first-episode schizophrenia patients predominantly increases the risk for lipid and glucose metabolism abnormalities.