High average power Nd:YAG lasers are increasingly interesting for industrial applications such as drilling and machining. Diode pumping of this solid state medium offers longer services intervals, reduced thermal optical distortions, higher system efficiency and more compact packaging than lamp pumping. The zigzag slab geometry is well suited for applications where the average power exceeds a few hundred watts and a good beam quality is desired, particularly if the laser pumping level is to be varied. We present the status of our latest upgrade to our (originally 300 watt1) diode pumped slab laser. In what follows we first describe the diode pump source. We then discuss the zigzag slab laser design and its present performance.