The subset of patients with late-life onset of bipolar disorder is widely recognized to represent an etiologically diverse group with high rates of neurologic comorbidities., Efforts to characterize the unique clinical and neurobiological features of this heterogeneous population have yielded inconsistent findings., Although there is growing evidence that geriatric-onset bipolar disorder is often attributable to a variety of secondary organic etiologies, we would like to present a case of bipolar disorder emerging in late life where no clear organic cause was identified. This case highlights the importance of a broad differential diagnosis when approaching new-onset manic symptoms among geriatric patients in an inpatient setting.