The workflow technology has been introduced in order to model and manage business processes, but workflows have some disadvantages as the formal verification of their correctness is difficult. A solution for this problem, can be the modeling of workflows by means of using Petri Nets, which are expressive, have a well defined semantic, a very accessible graphical representation and reach techniques for checking quantitative and qualitative properties. A workflow represents the automatization of a complex process which consists of a set of interdependent activities, orientated towards the fulfilling of a certain objective. The applicability domains of workflows are: the modeling, the coordination, the management of business processes. Workflows are based on cases, which are generated by external clients or they are generated internally. A case is an instance of a workflow. A workflow process is designed to handle similar cases, specifying what action must be executed and in what order. In this article we will define and use Time Workflow nets for modeling workflows, because Petri nets have well-known three advantages: simplicity, generality, and adaptability.