Our aim was to study the role of the Ottawa and Pittsburgh rules to reduce the unnecessary use of radiographs following knee injury. We prospectively reviewed 106 patients who were referred to our clinic over a 3-month period. The Ottawa and Pittsburgh rules were applied to individual patients to evaluate the need for radiography. One hundred and one patients (95%) had radiography of their knee. Five patients (5%) had a fracture of their knee and in all cases, the Ottawa and Pittsburgh knee rules were fulfilled. Using the Ottawa rules, 27 radiographs (25%) could have been avoided without missing a fracture. Using the Pittsburgh rules, 32 radiographs (30%) could have been avoided. The Ottawa and Pittsburgh rules have a high sensitivity for the detection of knee fractures. Their use can aid efficient clinical evaluation without adverse clinical outcome and may reduce healthcare costs.