Brachial amyotrophic diplegia (BAD) is a rare segmental form of motor neuron disease which presents with asymmetric lower motor neuron weakness largely confined to the upper extremities (UE). In the case being reported, a 62-year-old gentleman on antiretroviral treatment since 1993, presented with left-arm weakness in 2007 that quickly progressed to involve the right arm. Complete HIV-viral load suppression had been achieved since 2003. Examination revealed lower motor neuron weakness in both UEs, worse proximally than distally and normal strength in the lower extremities (LEs). Nerve conduction studies showed reduced amplitudes of bilateral median and ulnar nerves' motor responses. Needle electromyography of bilateral UE showed active and chronic denervation/reinnervation changes with normal findings in both LEs. MRI of the cervical spine showed cord atrophy. This is the first case report describing a patient who presented with BAD in the setting of complete HIV-viral load suppression for many years.