Oxidopamine, also known as 6-hydroxydopamine (6-OHDA) or 2,4,5-trihydroxyphenethylamine, is a neurotoxin used by scientists to selectively kill dopaminergic and noradrenergic neurons. 6-OHDA enters the neurons via the dopamine and noradrenaline (aka norepinephrine) reuptake transporters. Oxidopamine is often used in conjunction with a selective noradrenaline reuptake inhibitor (such as desipramine) to selectively kill dopaminergic neurons only. The reverse is also possible, however it is rarely done in research.

The main use for oxidopamine in scientific research is to induce Parkinsonism in laboratory animals such as mice, rats and monkeys, in order to develop and test new medicines for treating Parkinson's disease in humans. In order to induce this condition in animals, around 70% of the dopaminergic neurons in the substantia nigra of the brain must be destroyed, and this is achieved either with oxidopamine or MPTP. Both these agents likely destroy neurons by generating active oxygen species such as superoxide radical. Oxidopamine toxicity in neonatal rodents is also used as an animal model for the Lesch-Nyhan syndrome.