The effect of the neuropeptide galanin (GAL) on the basal and the evoked release of acetylcholine (ACh) was investigated in the rat striatum using microdialysis and HPLC techniques. GAL (0.3, 1 and 3 nmol), applied in the lateral ventricle (10 microliters), was found to cause a dose-dependent stimulation of the basal ACh release. The stimulating effect of GAL on ACh release was longlasting (greater than 90 min) and reached its peak 30 min after i.c.v. administration. GAL failed to affect the scopolamine (0.25 and 0.5 mg/kg, i.p.) stimulated release of ACh. Possible mechanisms behind the GAL-stimulated ACh release in the rat striatum are discussed. It may involve effects on GAL receptors in the striatum or indirect effects via stimulation of GAL receptors in the substantia nigra resulting in inhibition of striatal dopamine (DA) transmission.