The 30 item Maudsley Obsessional-Compulsive Inventory (MOCI) was given to 294 under graduate students. The inventory achieved an acceptable internal consistence, but somewhat low reliability. There were no sex difference in total MOCI score, or in any of the subscales. 31% of the variance seemed to be explained by item 18: "attending too much to details", and more than 65% of the variance is explained by the checking subscale. The data give some interesting indications of the prevalence of OCD in the population.