The psychiatric records of a 7-year period were searched for cases with seasonal mood disorders. Among 358 cases with a mood disorder there were 41 patients with 3 or more admissions, 4 of which were demonstrating a seasonal pattern. It was found that the depressive or manic episodes of these patients were anniversary reactions associated with intense traumatic experiences in childhood, adolescence or adulthood. The seasonal pattern of the depressive episodes fulfilled the DSM-IV diagnostic criteria. The time and sometimes the place of the traumatic event acted as triggers eliciting the clinical symptoms. This study showed that anniversary reactions may constitute a subgroup of seasonal mood disorders manifesting both depressive and manic episodes, which are precipitated primarily by psychological factors rather than climatic conditions.