Simplified debris, Calculus and oral hygiene indices of 145 mental Disorders examined in order to appraise oral hygiene status were Calculated and compared wicth the findings of other investigators. The obtained results were as follows; 1) Oral hygiene status of mental Disorders was very poor and became worse by ageing 2) Sexual characterics influenced slightly to oral hygiene status 3) No salient differences were found in the oral hygiene status among the intellegence quotient groups