Obsessive–compulsive disorder (OCD) has a multifactorial genetic basis, resulting from the action of several genes and environmental factors. To extend information on the genetics of this disorder, we examined an Italian population sample composed of 72 healthy graduate or undergraduate students of Sapienza University of Rome for association of OC symptoms, perfectionism, and personality traits, with known polymorphisms of tryptophan hydroxylase 2 (TPH2), serotonin transporter (5-HTT) and receptor 5-HT2A, dopamine receptors DRD2, DRD3 and DRD4. Results obtained may contribute to pinpoint TPH2, DRD2 and DRD3 as vulnerability factors in specific behavioral/psychopathological dimensions and represent a further step in the definition of phenotypic OC/perfectionistic behaviors of genetic relevance, ready to be further investigated in other populations.