Newer antidepressants are often prescribed to geriatric patients with depression because older agents often have side effects that may be problematic in the elderly. Less well-understood are the prescribing patterns of clinicians when such first-line agents are switched or augmented. OBJECTIVE: To examine switching and augmentation patterns used during the inpatient and post-discharge period in geriatric patients with major depression (ICD-9-CM codes 296.20-296.36) treated initially with fluoxetine, mirtazapine, sertraline, or venlaxafine. METHOD: Data were obtained from the CQI+SM Outcomes Measurement System, an ORYX (JCAHO) accepted performance improvement system, which tracked patients admitted to geropsychiatric inpatient programs in 111 general hospitals across 33 states between 1997- 1999. A Medication Usage Questionnaire was used to track medications prescribed just prior to admission, at time of discharge, and at three-month post-discharge follow-up. RESULTS: From admission to discharge, over one-third to one-half (37.4 - 52.1%) of patients switched or augmented specific antidepressant agent. Switching and augmenting rates decreased somewhat from discharge to follow-up (10.5 – 29.6%) and from admission to follow-up (30.5 – 38.9%). Remarkably, over twenty distinct antidepressant agents were used when switching occurred, and fifteen distinct antidepressant agents were used to augment the initial antidepressant agent. CONCLUSIONS: A significant number of patients do not appear to improve adequately on their agent of first choice. The great variety of treatment combinations suggests there is no clearly preferred treatment strategy for partial and non-responders. Practice guidelines for treatment strategies to augment and switch in older patients with depression would be beneficial for both clinicians and patients.