The Web browser is an excellent environment for the rapid development of an effective and inexpensive PACS viewer. In this paper we will share our experience in developing a browser-based viewer, from the inception and prototype stages to its current state of maturity. There are many operational advantages to a browser-based viewer, even when native viewers already exist in the system (with multiple and/or high resolution screens): (1) It can be used on existing personal workstations throughout the hospital. (2) It is easy to make the service available from physician's homes. (3) The viewer is extremely portable and platform independent. There is a wide variety of means available for implementing the browser- based viewer. Each file sent to the client by the server can perform some end-user or client/server interaction. These means range from HTML (for HyperText Markup Language) files, through Java Script, to Java applets. Some data types may also invoke plug-in code in the client, although this would reduce the portability of the viewer, it would provide the needed efficiency in critical places. On the server side the range of means is also very rich: (1) A set of files: html, Java Script, Java applets, etc. (2) Extensions of the server via cgi-bin programs, (3) Extensions of the server via servlets, (4) Any other helper application residing and working with the server to access the DICOM archive. The viewer architecture consists of two basic parts: The first part performs query and navigation through the DICOM archive image folders. The second part does the image access and display. While the first part deals with low data traffic, it involves many database transactions. The second part is simple as far as access transactions are concerned, but requires much more data traffic and display functions. Our web-based viewer has gone through three development stages characterized by the complexity of the means and tools employed on both client and server sides.