The book describes the use of simple and higher order Petri Networks for modeling queues of various types in business processes. Simple Petri Networks are used to describe cyclic queues, including priority ones. Models of time and color networks of Petri have been developed for the study of mass service systems with one-line and multi-line, single-channel and multichannel queues.The indicators of their efficiency are defined: productivity, length, waiting time, requirements for structures.