Superior oblique muscle palsy is not only the most frequent cause of acquired vertical strabismus, anomalous head posturing and torsional diplopia, but also the most common isolated oculomotor paralysis seen in everyday ophthalmic practice. Adults typically present to the ophthalmologist with asthenopic symptoms of long duration, while children present with objective clinical signs. An understanding of the available subjective and objective examination techniques will enable the clinician to diagnose the presence of this cyclovertical muscle paralysis. There are clues from the examination that suggest a superior oblique palsy of long duration, which may save the patient a needless neurological workup and a 6-month wait before surgical options can be considered. There are also clues from the examination that suggest the presence of a "masked" bilateral superior oblique palsy. Most cases of previously diagnosed skew deviation, if examined closely, will actually turn out to be mild trochlear nerve pareses.