MATERIALS and METHOD: The study was done between December 13 th, 2007 and January 11 st, 2008 in the patients from Haodeid and Doikiree Communities with moderately to very severe knee osteoarthritis which classified by index of severity for knee osteoarthritis (knee ISOA) and joined Knee Osteoarthritis Self-Health Care Project in community during December 13th to 14th, 2007. Confirmed diagnosis was done by history taking, physical examination and radiography. The KOOS (knee and osteoarthritis outcome score) was done for baseline assessment. After education about disease and suitable activities, they received simple home-based exercise program, isometric quadriceps exercise and open chain quadriceps exercise, for 4 weeks before measured by the KOOS again. The obtained data was analyzed and presented by frequency, percentage, mean, standard deviation and paired t-test with significant level at 0.05.