This study measured the cerebellar volume of normal male adults in 20s with magnetic resonance imaging (MRI) and analysed the relationship between cerebellar volume and various psychological parameters. The cerebellar volume of 58 males (mean age, 24.0 +/- 2.8 years) was measured using MRI. The Symptom Checklist-90-R (SCL-90-R) and the Component of Type A Behavior tests were performed. Using linear regression analysis, the relationship between cerebellar volume and psychological parameters was analysed. As phobic anxiety and ambition increased, cerebellar volume of normal male subjects in 20s decreased. This study showed that for even normal male adults, there exists a possible relationship between various psychological parameters and cerebellar volume. (C) 2013 The Authors. Published by Elsevier Ltd.