Background This study investigates changes in metabolic parameters in prepubertal children after 14–16 weeks of treatment with low‐dose risperidone. Method Thirty‐one children (mean age 5.46 ± 1.98 years) were treated with risperidone (0.25–1 mg/day; 0.01–0.07 mg/kg/day). Patients were excluded if they were using any medication other than risperidone or were diagnosed with any medical problem in addition to a non‐psychotic disorder. Results Weight (Δ: 2.51 ± 1.94 kg), height (Δ: 0.03 ± 0.04 cm), BMI (Δ: 0.82 ± 1.4), BMI percentile (Δ: 9.72 ± 16.40), BMI z‐score (Δ: 0.33 ± 1.03), triglyceride (Δ: 1.50 ± 23.97 mg/dl), very low density lipoprotein (Δ: 2.99 ± 4.76 mg/dl), insulin (Δ: 3.07 ± 3.38 mIU/ml), and leptin (Δ: 3.02 ± 4.69 ng/ml) were significantly increased (p < .05). Conclusion The metabolic side effects of risperidone must be carefully monitored in prepubertal children.