1. Unilateral denervation of the rat vas deferens (RVD) was performed under anesthesia. The animals were allowed to recover 4 or 10 days and then concentration-effect (C-E) curves to noradrenaline (NA) and neurokinin A (NKA) were constructed in denervated and control RVD. 2. Tissues denervated 4 or 10 days produced NA responses shifted 20-fold to the left with maxima 130% of control. 3. NKA C-E curves in denervated RVD were not significantly different from control. 4. Phenylephrine exhibited a 6-fold increase in tissue sensitivity after denervation. 5. Chronic denervation of the vas deferens resulted in significant postsynaptic supersensitivity to alpha 1-adrenoceptor agonists but not to NKA.