WinRHlZO™ is a new root measuring system (1993) based on an optical scanner instead of a video camera. Scanners produce high-quality images, free of illumination problems, over large areas (typically 11 × 17 inches). They are also extremely easy to use, and do not need to be recalibrated each time the optical set up or the resolution is changed. Different lighting systems are also available. WinRHlZO™ is an interactive system; the user can see on screen with color codes what the system is measuring and can make corrections if needed. WinRHlZO™ has the capacity to detect overlapping root parts and to compensate for them in the final results. It measures total length, projected area, surface area, and root length for different width intervals chosen by the user. The results are shown in a printable histogram placed above the image. The system also counts root tips and branching points. It is possible to verify the width at different points along the root by clicking them in the image. WinRHlZO™ can analyze whole images or different parts of them. It runs on IBM-compatible software under Microsoft Windows 3.1 or NT, and on Macintosh computers.