We report one case with isolated unilateral superior branch oculomotor nerve palsy due to an erosive sphenoid sinusitis. Within 8 weeks after surgical drainage of the sphenoid sinusitis, the patient recovered fully from the superior branch oculomotor palsy. In view of the dramatic clinical improvement that followed surgery, we hypothesized a compression of the superior branch of the oculomotor nerve by the sphenoidal abscess. To our knowledge, this is the first reported case of a superior branch oculomotor nerve palsy related to an erosive sinusitis and cured by sinusotomy, a safe and simple surgical procedure. Thus, we believe that our observation bears some practical implications of clinical importance in the management of patients who present partial oculomotor nerve palsy.