A picture archiving communication system for storing, transferring various digital image data in a single or a plurality of hospitals includes a modality, a data base, a workstation as a display unit, and a network for connecting these components. The modality includes various diagnosis apparatuses for generating medical digital images, such as a film digitizer, an angiography apparatus, a CT scanner, an MRI system, a nuclear medicine diagnosis apparatus, an ultrasound diagnosis apparatus, and an electric endoscope. An examination ordering system is connected to the network. The workstation outputs computer-aided diagnosis data obtained by analyzing medical image data by means of a computer. This computer-aided diagnosis data includes the location, the type, and the degree of abnormality. In order to alarm an abnormality, the workstation displays a marker pointing the portion of the abnormal portion on the image, a text sentence representing the details of the abnormality. The computer-aided diagnosis data is obtained before its output is requested. The computer-aided diagnosis data is stored in a semiconductor memory until its output is requested.