SUMMARY Sixty male criminals selected randomly from the Central Prison of Madras and twenty mentally ill criminals from the Institute of Mental Health, Madras, were administered E.P.Q. and compared with sixty normals. The results show that criminals scored significantly nigh on extroversion, psychoticism and neuroticism. The mentally ill criminals scored significantly on psychoticism compared to normals. Criminals and mentally ill criminals do not differ significantly on any of the scales of E.P.Q.