Angiotensin II and angiotensin III stimulated protacylin release in a time- and dose- dependent manner in both the prostatic and the non-prostatic part of the rabbit vas deferens. Also, angiotensin I enhanced the production of prostacyclin and its effect was blocked by captopril. Losartan, a type 1 (angiotensin AT₁)-selective receptor antagonist, prevented the angiotensin II-induced prostacyclin release. The agonist peptide, p-aminphenylalanine⁶ angiotensin II, and the type 2 (angiotensin AT₂)-selective receptor antagonist, PD123319, were found active only in the prostatic portion, suggesting heterogeneity of the receptor population. In conclusion, an angiotensin AT₁ receptor mostly mediates the angiotensin-induced release of prostacyclin in the rabbit vas deferens.