Oxidopamine (6-Hydroxydopamine) is an antagonist of the neurotransmitter dopamine with potential antineoplastic activity. 6-Hydroxydopamine (6-HOD) can be taken up by selective adrenergic terminals, thereby causing acute degeneration of adrenergic terminals that leads to depletion of norepinephrine, and of dopamine in the dopamine-sensitive sites. This agent is auto-oxidated at physiological pH that leads to the formation of reactive free radicals, thereby leading to cytotoxicity in neural cells. 6-Hydroxydopamine is often used to induce CNS and sympathetic neural lesions that model aging and various nervous disorders in animal systems. The growth of C-1300 neuroblastoma was markedly slowed in 6-hydroxydopamine-treated mice. The growth of the A-10 breast adenocarcinoma was also significantly retarded in 6-hydroxydopamine-treated mice but the growth of B-16 melanoma was not affected.