The size of a typical data transfer in a PACS environment is several orders of magnitude larger than a typical data transfer in a local area computer network. PACS is also moving to a multi-vendor environment. To ensure reasonable response times to users, it is necessary to manage the image traffic on the PACS network explicitly, and for the heterogeneous network environment, tools for monitoring and maintenance are necessary. Modular network architectures, capable of reacting to growth and changes in traffic patterns, are essential. Knowledge about patient-radiologist and image flow which is available in the hospital environment can be exploited for careful planning and scheduling of network traffic. The authors designed and implemented a prototype network management system that makes the domain knowledge and the traffic management strategy explicit. In general, the term network management covers a wide range of tasks. Network design and configuration, for example, are network management tasks situated in the pre-operational phase. Network monitoring and control, including error detection, fault diagnosis, dynamic routing, etc., are network management tasks with a real-time aspect. This PACS is hierarchically organized. Each sub- department has its own local PACS. The paper focuses on the results of the implementation of the PACS architecture and, more precisely, on the network management aspects.