Non ossifying fibroma or fibrous cortical defects are common benign proliferations of fibrous tissue that occur in metaphyseal regions of long bones. Many are asymptomatic and are found incidentally on routine x rays done for other reasons. Fibrous cortical defects associated with other diseases are rare and sparsely reported. We describe a case of fibrous cortical defect lower end of femur with rheumatoid polyarthritis occurring in the same patient.