MRI is a multiparametric, multiplanar, non-invasive largely employed tool for assessing osseous, ligamentous and tendineous injuries, inflammatory and degenerative changes of the knee. Although its wider availability and the lack of ionizing radiations MRI should be used only if clinically useful in patient management, in a appropriate diagnostic iter including plain film and/or ultrasound examination. The aim of our work is to review possibilities, limits and current indications for MRI assessment of diseases of the knee.