This paper presents the application of open queueing networks BCMP in optimization of organizing structure as exemplified by an out-patient clinic. The mode of operation of the clinic has been discussed and a mathematical model of queueing network has been proposed. Parameters that describe the network operation have been determined, i.e. the average number of patients in each doctor's office, the average duration of a visit and the average time spent on the premises. These parameters have been employed in assessment of clinic efficacy. Structural changes aiming at optimization of the clinic operation have been proposed.