This in vivo study recorded the microleakage and marginal discrepancies of cast glass-ceramic cemented crowns compared to gold onlays and a metal ceramic restoration. Within the limits of the small number of samples and the variables inherent in an in vivo study, it was found that (1) dentin bonding agents are not strong enough to produce a gap-free cementation, (2) the marginal adaptation of beveled metal restorations is better than that of glass-ceramic crowns, and (3) the marginal adaptation of cast glass-ceramic crowns is clinically acceptable.