1. We compared the binding properties of [3H]-desArg10-[Leu9]-kallidin, a radiolabelled kinin B1 receptor antagonist, to membranes from IMR-90 human embryonic fibroblasts and from 293 cells transiently or stably transfected with the human B1 receptor. 2. The dissociation constant (KD) of [3H]-desArg10-[Leu9]-kallidin and the affinity of several kinin receptor agonists and antagonists were similar between the native and cloned receptor, either transiently or stably expressed in 293 cells. In IMR-90 cells, the rank order of potency was that expected for a kinin B1 receptor. 3. The receptors transiently or stably expressed in 293 cells were fully functional with respect to their signalling properties. Phosphoinositide hydrolysis was increased in a concentration-dependent manner by the B1 receptor agonist, desArg10-kallidin. Functional coupling to the calcium pathway was also demonstrated for the native and stably expressed human B1 receptor. 4. In conclusion, the established stable and functional 293 cell clone may provide an important tool for further analysis of the molecular mechanisms involved in binding, activation, and coupling of the kinin B1 receptor.