Dynamic orbitotonography was done in 17 patients with Graves' disease, 25 patients with orbital tumours and 15 healthy subjects. The mean orbital pressure for both patient groups was significantly different from that for the healthy subjects at each time interval (p less than 0.001). Healthy patients may be differentiated from those with orbital disease with a good degree of reliability with this technique. As well, the technique may provide information about the location of disease within the orbit.