Software modules for interactive display, manipulation and retrieval of medical images have been designed for a Picture Archiving and Communications System (PACS). The target of these modules is not for a high-end diagnostic workstation for radiologists, but for a PC-based low cost clinical workstation for a referring physician. This software is constructed based on a concept of an object-oriented language which is designed to be modular and expandable. It consists of several functional modules: (a) a communication module for image retrieval, (b) a standard module for the interpretation of the DICOM images, (c) a user interface module for the non-computer oriented clinicians and (d) a tool module for viewing and manipulating images as well as editing the annotation.