[Deamino-Cys^l, _D-Arg⁸]-vasopressin (dDAVP), known to be an arginine vasopressin (AVP) V₂-receptor agonist, is an agent which increases fibrinolytic activity levels in plasma after its infusion into the human body. However, mechanisms underlying an increase and exact localization of extra-renal dDAVP-responsive V₂ receptor remain unclarified. Two AVP receptors, V_1a and V₂, and a related oxytocin (OT) receptor were found to be expressed in human lymphocytes. Further, we found the increase of fibrinolytic activity in the medium of the peripheral lymphocytes obtained from human volunteers less than 20 minutes after dDAVP infusion. The increased activity was also detected in the medium after incubating the lymphocytes in the presence of dDAVP in vitro, being highest at 20 minutes after the incubation. In accordance with the increased fibrinolytic activity, the levels of urokinase-type plasminogen activator (uPA) in the medium were also increased. However, there was no significant difference of plasminogen activator inhibitor-1 (PAI-1), pro-uPA, and tissue-type plasminogen activator (tPA) concentration in the medium between dDAVP treatment and control. When lymphocytes were pre-incubated with a V₂-receptor antagonist, [Adamantaneacetyl¹, O-Et-_D-Tyr², Val⁴, Aminobutyryl⁶, Arg⁸, ⁹]-vasopressin, the dDAVP-induced uPA increase was diminished. In contrast, pre-incubation with a V₁-receptor antagonist, [-Mercapto-, -cyclopentamethylenepropionyl¹, O-Me-Tyr², Arg⁸]-vasopressin, prior to dDAVP treatment resulted in more increase of the uPA concentration in the medium than the dDAVP treatment alone. Thus, it was suggested that dDAVP may induce uPA release from human lymphocytes via V₂-receptor-mediated reaction and moreover via cross-talk between V₁ and V₂ receptors.