This paper describes the Power System Blockset (PSB) from The MathWorks, Natick, MA, which is a new software package for the simulation of electric circuits, power systems, power electronic devices, and electric drives. The PSB is developed in the graphical Simulink environment of the general-purpose Matlab software. This blockset inherits a number of advantages from its development environment, namely, an open architecture, a powerful graphical user interface, and versatile analysis and graphics tools. The user can integrate control systems implemented with Simulink blocks directly into a diagram built with the PSB. Solution of differential equations is accomplished using the state-space approach with variable-step variable-order integration algorithms. A simulation example is presented, and the results are compared with those obtained with PSPICE.