Biogenic monoamine disorders are a group of inherited diseases characterized by a defect in the synthesis, transport, or degradation of catecholamines and serotonin. The phenotype mostly reflects the pattern and severity of the monoamine deficiency. Movement disorders due to cerebral dopamine deficiency are almost always prominent, mostly in the form of dystonia and/or parkinsonism. These disorders are potentially devastating yet treatable. Early diagnosis and treatment are crucial to prevent ongoing brain dysfunction. Detection of hyperphenylalaninemia in a neonate could be a good clue to the diagnosis. Final diagnosis is often based on a detailed biochemical investigation of the cerebrospinal fluid and can be confirmed by molecular analysis. Treatment is aimed at restoring neurotransmitter homeostasis using monoamine precursors, monoamine agonists, and inhibitors of monoamine degradation. It also comprises the control of hyperphenylalaninemia and the prevention of cerebral folate deficiency, when applicable.