The purposes of the present study were to compare the effects of viscoelastic materials available in phacoemulsification in dogs and to evaluate $ARTZ^{circledR}$ as their substitute. Six eyes from the healthy adult dogs were used in each group with different viscoelastic materials, $Healon$^{circledR}, Viscoat^{circledR}$ and $Occucoat^{circledR} and ARTZ^{circledR}$. The phacoemulsification was carried out with surgical micmscope(Leica M65l, Germany) and pbacoemulsiscation gystemGfidek 6000, Japan). $ARTZ^{circledR}$ had lower pseudoplasocity than other viscoelastics. There was not significant difference in phacotime, rate of posterior capsule rupture, incidence of the intraocular inflammation among the viscoelastic materials. The corneal thickness in all groups was significantly increased in a day after operation and decreased gradually. However $ARTZ$^{circledR}$</TEX> had more time to recover the preoperative thickness than the others. CoBiunctival congestion in the group with $ARTZ^{circledR}$ was more severe but. there were no postoperative posterior capsule opacity and visual loss. The present study indirated that $ARTZ^{circledR}$ could be used as viscoelastic material in dogs with respect to the vision after surgery.