Treatment-resistant depression is an important clinical problem presenting a major challenge to clinical psychiatry. While several strategies have been attempted, including medication switch, antidepressant polypharmacy and various augmentative regimens, success remains limited. Amantadine (AMN), an agent traditionally used in the treatment and prophylaxis of influenza, is now known to exhibit prominent effects at the level of dopaminergic, monoamine oxidase and N-methyl-D-aspartate systems. The present reports on the efficacy of AMN as augmentation to standard antidepressant treatment in patients with treatment-resistant depression. Eight patients with treatment-resistant depression consented to receive AMN, titrated up to a dose of 300 mg, over a period of 4 weeks in a non-blinded fashion. Improvement in both depression and anxiety scores were observed from week 1, with patients exhibiting improvement of depressive scores of up to 49% by study completion. Females appeared to exhibit a stronger response, and within a shorter period of time. Side-effects reported included dry mouth and sedation. AMN appears to demonstrate efficacy as a safe and effective augmentative agent in treatment-resistant depression. Further studies are clearly mandated to test these preliminary observations in a double-blinded manner.