To study the influence of bonding agent on fracture strength of Plat-II castable ceramic crowns bonded to molars, we tested the specimens in vitro with Panavia 21 resin bonding agent and porcelite dual cure cement. The results showed that the fracture loading (845.8 +/- 137.1 N) of crowns bonded with Panavia 21 bonding agent was higher than that (534.0 +/- 58.7 N) of crows bonded with porcelite dual cure cement. The difference between the two agents was statistically significant (P < 0.05). The crowns bonded with Panavia 21 agent had higher strength than bite forces. These suggest that costable ceramic crowns could be bonded with Panavia 21 resin agent in clinical practice.