The aim of this randomized controlled trial was to evaluate the clinical performance of lithium disilicate fixed partial dentures (FPDs). Eighteen patients received lithium disilicate FPDs (study group), and 19 patients received porcelain-fused-to-metal FPDs (control). After 6 years, the survival probabilities were found to be 63% in the study group and 95% in the control group (log-rank test, P = .028). The data suggest that strict conditions should be considered before the use of lithium disilicate glass-ceramic for FPDs.