Background Information about differences between younger and older patients with bipolar disorder and between older patients with early and late age of onset of illness during long‐term treatment is scarce. Objectives This study aimed to investigate the differences in treatment and treatment outcome between older and younger manic bipolar patients and between early‐onset bipolar (EOB) and late‐onset bipolar (LOB) older patients. Method The European Mania in Bipolar Longitudinal Evaluation of Medication study was a 2‐year prospective, observational study in 3459 bipolar patients on the treatment and outcome of patients with an acute manic or mixed episode. Patients were assessed at 6, 12, 18, and 24 months post‐baseline. We calculated the number of patients with a remission, recovery, relapse, and recurrence and the mean time to achieve this. Results Older patients did not differ from younger bipolar patients in achieving remission and recovery or suffering a relapse and in the time to achieve this. However, more older patients recurred and in shorter time. Older patients used less atypical antipsychotics and more antidepressants and other concomitant psychiatric medication. Older EOB and LOB patients did not differ in treatment, but more older LOB patients tended to recover than older EOB patients. Conclusion Older bipolar manic patients did not differ from younger bipolar patients in short‐term treatment outcome (remission and recovery), but in the long term, this may be more difficult to maintain. Distinguishing age groups in bipolar study populations may be useful when considering treatment and treatment outcome and warrants further study. Copyright © 2014 John Wiley & Sons, Ltd.