Patients with osteoarthrosis of the knee were taught two simple exercises to be practised daily with graduated weights, recording the details in an instruction/record book. Patients were randomly divided into those receiving treatment (and short-wave diathermy) at hospital (group A), and those doing their exercises at home (group B). Both groups showed decreased pain and increased function, maximum weight lift and endurance at the end of 4 weeks. There was no difference between the groups. Benefit was retained by most of those patients notified at 6 weeks of a further assessment session at 12 weeks; most of these subjects continued daily exercises, whereas those not notified in advance were more likely to cease exercising and experience more pain. The exercise regimens are easy to perform and document. It is suggested that if such regimens were routinely used there would be great practical benefits for patient and physiotherapist.