The issue of appropriate structure of service system to adopt is becoming a serious challenge to the designer of a system. A good system design has the tendency of ensuring high productivity and efficiency. This paper examines the determinants of structure of service system through queue system approach. This study is one of the several works that recognises that the cost element must be taken into consideration whenever an organisation attempts to design a structure for the service system. To design a system that is more effective, the paper concludes that the format depends on the volume of customers served, randomness of arriving population and partly on the restrictions imposed by sequential requirements as to the order in which it must be performed. The paper recommends that to design a system that is more effective in terms of being able to reduce the waiting time in the queue and ensure a quick service delivery an appropriate system structure must be put in place based on size, volume of calling population and cost.