A functional polymorphism in the upstream regulatory region of the serotonin transporter gene (5-HTTLPR) has been recently reported to be associated with mood disorders. In the present study we investigated the possible influence of 5-HTTLPR on the symptomatology of mood disorders. Two hundred and thirty inpatients affected by mood disorders (160 bipolar and 70 major depressive disorder) were assessed by the Operational Criteria checklist for psychotic illness (OPCRIT) and were also typed for the 5-HTTLPR variants using PCR techniques. Mania, Depression, Delusion and Disorganization were the four symptomatologic factors used as phenotype definition. 5-HTTLPR variants were not associated with these symptomatologic factors, and consideration of possible stratification effects, such as sex, age of onset and polarity, did not reveal any association either. The serotonin transporter gene does not, therefore, appear to be associated with the symptomatology of mood disorders.