KNOWLEDGE ABOUT HEALTH CARE RIGHTS AMONG A GROUP OF CHILEAN PATIENTS WITH KNEE OSTEOARTHRITIS Background: Mild to moderate osteoarthritis of the knee in people over 55 years of age is one of the diseases whose management is covered by the explicit guaranties in health system (GES) in Chile. All beneficiaries with the disease should be informed about their rights to receive free treatment. Aim: To assess the degree of awareness about their rights among patients with knee osteoarthritis, admitted to GES.  Material and methods: Two hundred forty one patients aged 55 to 93 years (180 women) with knee osteoarthritis admitted to GES, answered at their homes a survey about their rights to receive health care, included in the GES system and about their disease.  Results: Fifty percent of patients did not know what GES system was, 26% admitted to have a limited knowledge and 24%, a full knowledge. Sixty two percent were not informed about the nature of their disease and 42% perceived their health as less than optimal. There was a significant association between the level of knowledge about GES and osteoarthritis  and their self-perception of health. Conclusions: Half of the patients with knee osteoarthritis surveyed, were not aware of their health care rights included in GES and  received scanty information about their disease.