Arthroscopic visualization of the posteromedial compartment of the knee via an anterolateral portal is not commonly practiced, yet it is relatively simple, has low morbidity, and is of diagnostic and therapeutic value. This prospective study evaluates posteromedial visualization of the knee joint in a series of 117 consecutive patients who underwent arthroscopy for diagnosis or treatment, or both, of 209 pathologic conditions. The technique was deemed simple to perform in 78% of patients. It was found to be more difficult in knees with degenerative joint disease. Posteromedial visualization was found to be essential for diagnosis or treatment in 4% of the diagnosed conditions, and helpful in an additional 13%. The technique was most useful for tears of the posterior horn of the medial meniscus, some of which were not detected by visualization from the anteromedial compartment alone. Visualization of the posteromedial compartment was deemed adequate in 89% of the patients, and there was no morbidity.