In unilaterally 6-hydroxydopamine lesioned rats the ability of two non-peptide δ-opioid agonists, BW 373U86 and SNC 80, to induce motor asymmetries, alone or in combination with low doses of specific D1or D2agonists, was investigated. BW 373U86 and SNC 80 failed to induce motor asymmetries by themselves, but elicited contralateral turning after pretreatment with a dose of SKF 38393, a D1agonist, or quinpirole, a D2agonist, whichper sedid not induce contralateral turning. BW 373U86 also potentiated contralateral turning induced by threshold doses of quinpirole. Facilitation of D1-dependent contralateral turning was associated with a potentiation of c-fos expression, as estimated by Fos-like immunoreactivity, in the dorsal caudate-putamen, particularly in its lateral aspect. Potentiation of D2-dependent contralateral turning was associated with a reduction of c-fos expression in the medial caudate-putamen. It is concluded that stimulation of δ-opioid receptors facilitates the expression of D1and D2responses arising from the denervated striatum.