Age and other physical attributes may affect the presentation and management of depressive and bipolar disorders. Three of these populations are discussed in this paper. In young patients, mood symptoms are less clear-cut than in adults, and pharmacological treatment, if used, should be prescribed at low doses, with close observation for side effects. In the perinatal population, the diagnosis of depression hinges more on emotional than physical symptoms, as the latter may be a consequence of the gravid state. Treatment of mood disorders in this population is a delicate balance between the timely amelioration of harmful symptoms and the prevention of medication side effects in the child. In the elderly, sensitivity to the possible existence of depression is important for those who present primarily with chronic illnesses or recent bereavement. Mood symptoms may masquerade as physical complaints and medications should be used with care because of age-retarded drug metabolism.