OBJECTIVE Recent data from the literature have recognized the importance of cerebellum in bipolar disorder. Brain imaging studies focusing on cerebellar volumetric changes in bipolar disorder demonstrated controversial data. The aim of this study is to investigate whether there is any difference between early-onset bipolar cases and healthy controls regarding cerebellar volumetric measurements. METHODS Patients with bipolar I disorder were compared to healthy controls in terms of total cerebellar volume, volumes of the right and left cerebellar hemispheres, and cerebellar volumetric asymmetry. All the sociodemographic, clinical data, and magnetic resonance image scans were collected retrospectively. Cerebellar volumes were evaluated using the stereological method. Asymmetry indices were calculated subsequently. RESULTS We recruited 10 bipolar I cases and 10 healthy controls. There were no statistically significant differences between the bipolar and the control groups for total cerebellar volumes, volumes of right and left cerebellar hemispheres, and cerebellar asymmetry indices. CONCLUSION Future studies focusing on cerebellar changes in early-onset bipolar disorder should include large case and control series and designed as follow-up studies for being able to determine the chronic effects of the illness on cerebellar volumes.