We measured CSF and plasma contents of β-endorphin (β-EP), β-lipotropin (β-LPH), and ACTH in 24 patients with Parkinson's disease; 14 had not been treated. CSF β-EP concentrations in untreated patients were lower than in 15 controls (p < 0.005), but values did not differ significantly in treated and untreated patients. In untreated and treated patients, ACTH and β-LPH CSF, and β-EP, β-LPH, and ACTH plasma concentrations were in the same range as controls. The Parkinson's disease-related decrease of CSF β-EP levels further supports the concept that there is a generalized brain disorder in Parkinson's disease affecting more than dopaminergic neurons in the substantia nigra.