M.Tech. / Osteoarthritis (OA) is a common and severely disabling disease (I). Chiropractic mobilisation functions well to improve mobility, relieve pain and promote healing (2). Non-steroidal anti-inflammatory drugs (NSAIDs) are commonly used for the treatment of OA. Their role in OA, however, is not clearly understood (3). Adverse side effects and the cost of NSAIDs also remain a problem (4). Seatone is a health supplement that has therapeutic properties that provides symptomatic relief of OA by means of its anti-inflammatory action (5,6). Seatone produces a slow, but progressive relief from pain and stiffness and improves quality of life (7' 8). The purpose of this study was to determine the effect of Seatone on the treatment of OA. This was achieved by comparing Chiropractic mobilisation (in preference to Chiropractic manipulation) in conjunction with oral administration of Seatone to Chiropractic mobilisation or oral administration of Seatone alone, by means of subjective and objective measurements. The study required forty-five subjects, above the age of thirty-eight years, suffering from OA of the knee joint, according to the classification criteria (Appendix A). The subjects were screened according to the exclusion and inclusion criteria and all the relevant forms, questionnaires and clinical examinations were completed. The subjects were randomly assigned to one of three treatment groups. Treatment was conducted over a period of eight weeks. Objective or goniometer readings and subjective measurements were done prior to and following treatment to determine the effect of the therapies. The subjective measurements were taken from the Numerical Rating Scale (NRS), the Visual Analogue Scale (VAS) and the McGill Pain Questionnaire. The Cincinnati Knee Rating System, a comprehensive knee questionnaire, was completed at the initial and final consultation. A combined treatment of Chiropractic mobilisation and oral administration of Seatone or oral administration of Seatone alone showed a greater mean improvement than Chiropractic mobilisation alone, in mobility. There was no significant difference in the assessment of pain between the three groups. However, results show that Seatone has a positive effect in the treatment of OA of the knee, for improving mobility.