The description of a single-facility, single-consumable-item inventory model in which demands are Poisson, procurement lead-times are either deterministic or exponential, and a continuous review (s, S) replenishment policy is employed. An exact expression is derived for the steady-state expected time that a customer waits to be satisfied. Although this performance measure is not usually studied for inventory models, it is useful for imbedding the facility in a multi-echelon structure. 22 pp. Ref.