The recent trends in the computer industry are the one and only thing i.e., web services. Because of the common availability and open technologies web services are relevant to all. Service-oriented architecture (SOA) helps organizations to transform their business processes for high performance by simplifying the underlying information systems. The most challenging aspect of building successful software applications is clearly understanding and specifying the requirements that an application must satisfy. Use case modeling is an increasingly popular approach for identifying and defining requirements for software applications of all types. Use cases describe the behavior of the system as its users interact with it. This approach helps to place the software requirements in the framework of a user doing some useful work with the system. This type of approach helps to map software requirements to the relevant enduser business processes, a very powerful concept. This paper presents how the relationship between use case model and Service oriented architecture.