Summary: The definition of \(\alpha\)-cut and Zadeh’s extension principle are applied to transforming multiple-server fuzzy queues, of which the arrival rate and service rate are both fuzzy numbers, into conventional multiple-server queues. Then, the system eigenvalues are described separately by programming a set of parameters to solve upper and lower bounds of the relevant membership function. For instance, there is a 2-server fuzzy queues system of outpatients in a hospital, in which the average arrival rate and service rate are both regarded as trapezoidal fuzzy numbers. With a numerical computation of different \(\alpha\) levels, the membership function of the average staying time for all the outpatients can thus be solved. This method can provide more abundant information for managerial decision-making in hospitals.