Most of the methods which are used for the analysis and design of systems with parametric uncertainty require extensive computations. Therefore, it is value to develop computer programs which enable one to deal with uncertain systems in an easy way. This paper describes a user friendly software package(AISTK-Analysis of Interval Systems Toolkit). Algorithms have been developed in the MATLAB environment by using the Kharitonov theorem and related approaches. The objective in developing AISTK was to gather these algorithms under a toolkit and make them easily usable by students or other users. Copyright (C) 2000 IFAC.