Length-tension curves of detached eye muscles were continuously measured in albino rabbits with a length and tension measuring device developed by the author. The device consists of a strain gauge for measuring passive length-tension, and a position encoder equipped with an eddy current motor. In extending vertical rectus and oblique muscles, an exponential relation was found between length and tension. There was no significant difference between the passive load and extending velocity. The load of the superior rectus muscle was significantly greater than those of the other 3 vertical muscles, and that of the inferior oblique muscle was significantly greater than that of inferior rectus muscle. Each compliance of the inferior rectus muscle or the inferior oblique muscle was significantly greater than that of the superior rectus muscle or the superior oblique muscle.