Osteoarthritis is a chronic and degenerative disease characterized by pain and damage to joint cartilage, which often causes pain and limited movement in the elderly population to disrupt daily activities and cause severe socio-economic impacts. The risk factor is more than 50 years, female gender, obesity, history of knee trauma, and anatomical abnormalities. This study was conducted to determine the relationship between body mass index to the degree of genu osteoarthritis. The design of this study was observational analytic with a cross-sectional study approach, using consecutive sampling. The tools used are medical record paper, weight scales, staturmeter, X photo articulation genu. Parameters examined were gender, age, weight (BB), height (TB), grade osteoarthritis (OA) genu Kellgren-Lawrence. It is conducted at Tarakan Hospital, Jakarta. The results showed 67,5% of respondents were female, 67,5% of respondents with OA genu aged > 50 years, 67,5% of respondents with BMI ≥ 23, 17,5% OA genu with grade Kellgren-Lawrence 1, 22,5% OA genu with grade Kellgren-Lawrence 2, 30% OA genu with grade Kellgren-Lawrence 3 and 30% OA genu with Kellgren-Lawrence 4. Results of the chi-square test have a relationship between body mass index (p = 0.042) on the degree of osteoarthritis genu in Tarakan Hospital, Jakarta. It was concluded that there was a relationship between body mass index to the degree of osteoarthritis genu in Tarakan Hospital, Jakarta. Key words: Osteoarthritis, Body Mass Index, Grade OA Genu Kellgren-Lawrence.