This paper describes a software package based on a set of integrated tools intended to be used in nuclear medicine imaging environments. These tools, following a functionally consistent and open architecture, aim to provide an efficient and user-friendly way for handling the analysis and interpretation of nuclear medicine images in a broad range of applications. The Image, Graphics, and Colors tools are the basic building blocks. Besides basic image handling facilities, the Image tool was designed to accomplish both conventional and special purposed processing tasks. Among these, the interactive definition of organ shaped regions of interest, functional imaging (e.g., mean transit time images in ventilatory lung studies) and activity quantitation should be pointed out as the most intensively used facilities. The Graphics tool is used mainly to display and analyze the activity/time curves resulting from parametric related studies. As intensity color coding has gained wide acceptance in nuclear medicine it was thought convenient to implement a Colors tool intended to provide interactive intensity manipulation. The X Window graphics interface system is the basis for the implementation of this set of independent but intercommunicating tools which are intended to run on all UNIX workstations provided with, at least, an 8 bit depth frame buffer.