Some historical remarks on picture archiving and communication systems.

This Special Issue contains one Editorial and 15 papers. The Editorial reviews some key events, conferences, and publications which propel PACS to its current status. The fifteen papers describe current and future PACS research and development trends grouped in four categories: system-wide trends and clinical experience, tools, key technologies, and PACS-based applications. We see that PACS has gradually become a necessary tool for daily clinical operation, its future trends will be in the development of research methods to fully utilize its large image database for better healthcare delivery.