Primary care physicians have a vital role to play in identifying depression in their elderly patients. Diagnosis may be difficult, because symptoms are atypical and frequently include psychomotor agitation, somatic symptoms, and complaints of memory loss. Patients with medical illnesses, such as cancer, postmyocardial infarction, stroke, Parkinson's disease, and early Alzheimer's disease are particularly vulnerable to depression. Drugs that may cause depressive symptoms are digitalis at toxic levels, beta-blockers, centrally acting antihypertensives, immunosuppressants, and nonsteroidal anti-inflammatory agents. Cyclic antidepressants are the drugs of first choice. Selection depends on the patient's physical health and current medications and the side effect profile of the drug. Side effects are more pronounced in old age because of drug accumulation owing to slowed clearance. Troublesome side effects are anticholinergic effects, orthostatic hypotension, sedation, cardiotoxicity, and weight gain. The most useful antidepressants for geriatric patients are the secondary amines, desipramine and nortriptyline. The second-generation drug trazodone has the advantage of causing the least anticholinergic effects, but it is very sedating. Before treatment, the patient should have an electrocardiogram, liver function tests, tonometry, sitting and standing blood pressures, evaluation of urinary symptoms for outflow obstruction, review of current medications, and estimation of suicide risk. Cyclic antidepressants are contraindicated during recovery from myocardial infarction, in heart disease when there is severe impairment of myocardial performance, in seizure disorders, and in the presence of glaucoma or a large prostate. Drug interactions that may cause trouble can occur with epinephrine, MAO inhibitors, thyroid hormone, cimetidine, and centrally acting antihypertensives. Dosage should start low, increasing usually by 25 mg every 4 to 5 days until a therapeutic level is reached. Failure of a noradrenergic antidepressant after 4 to 5 weeks can be followed by a trial of a serotonergic drug. Drug serum level monitoring is useful for imipramine, desipramine, and nortriptyline. Monoamine oxidase inhibitors are effective in many elderly patients who are resistant to TCAs. Sympathomimetic drugs must be avoided with MAOIs. Elderly patients are at high risk of toxicity and drug interactions with lithium. Electroconvulsive therapy is useful for patients who do not respond to drug treatment, but medical complications, particularly cardiovascular, often occur in patients 75 or older. Many patients relapse after ECT. Psychotherapy together with pharmacotherapy may be the optimal treatment for elderly depressives. Older patients are more likely to become chronically depressed than younger patients. The risk of suicide in depressed elderly males is high, particularly in those with psychosocial problems, and depression rises with age.