In an attempt to provide further information on the functions of the serotonergic system in humans, we investigated the possible correlation between a peripheral serotonergic marker, such as platelet 3H-imipramine binding, and the Minnesota Multiphasic Personality Inventory (MMPI) items and scales in a group of 20 healthy subjects. The results showed the presence of significant positive correlation between the maximum binding capacity, a measure of the number of 3H-imipramine sites, and 17 MMPI items suggestive of personality features of self-certainty, feeling of well-being and sense of reality.