In this cross-sectional study we looked at the radiographic evidence of osteoarthritis (OA) of the knee in 300 randomly chosen patients attending 14 primary care facilities for different medical conditions. Radiographic OA was seen in 89 out of 167 males (53.3%) and in 81 out of 133 females (60.9%). The patella was involved with radiographic osteoarthritic changes in 80.7% and 87.8% of female and male OA patients, respectively. In most cases the medial compartment joint space was narrowed. Radiographic OA of the knee is very common in Saudi patients, especially in the patellofemoral compartment.