In Sydney, Australia, ten patients affected by superior limbic keratoconjunctivitis (SLKC) have been observed in one ophthalmic practice during a four-year period. Among the ten patients, three were found to be actively thyrotoxic, and two others had already undergone treatment for proven hyperthyroidism. Reference is made to a possible etiological contribution by the special anatomy of the upper conjunctival fornix and by secretions entering the conjunctival sac. The association with thyrotoxicosis revives the matter of an immunological (possibly auto-immune) origin for SLKC. A viral-induced mechanism has not been excluded.