When planning a Leksell GammaKnife? treatment, dose planners place iso-centres of the irradiation field in such a way that a certain iso-dose surface conforms as closely as possible to a target, such as a tumour. Today this planning is done primarily in 2D, and the clinician places the iso-centres onto the currentmedical image. The images used are usually acquired by MRI, CT or Angiography. In this paper we investigate the use of interactive 3D visualization and haptics to perform the dose planning. In a pilot implementation we provide the user with a virtual environment with real-time graphics to visualize the target, surrounding tissue and iso-dose surfaces as well as an integrated graphical user interface. The overall aim of the implementation is to increase the efficiency and precision of the planning process by adding haptic feedback to represent various constraints and opportunities in the planning process and so guide the user to an optimal placement of the iso-centres. Preliminary feedback from potential users has been very positive.