Osteoarthritis of knee joints is a disease of old age female sex. It is very common in post menopausal females. It is characterized by narrowing of space in joints due to inflammation. The exact mechanism of inflammation is not clear. The present study is being carried out in 150 female subject of age group 40-60 years suffering from osteoarthritis of knee joints and 50 normal healthy control female subjects of same age group. A correlation is made between TNF-α, IL-6 and estrogen hormone and found significant inverse correlation (< 0.001) between estrogen hormone and TNF-α, IL-6 in osteoarthritic female patients as compared to normal healthy control female age group. Estrogen hormone plays a bone protective effect of knee osteoarthritic disease.