OBJECTIVE Mechanical and optical studies of glass fiber composites have revealed great resistance and satisfactory bonds between the glass fibers and composite resins. This study aimed to evaluate the long-term survival of anterior and posterior direct glass fiber-reinforced composite (FRC) fixed partial dentures (FPD). METHODS Twenty-three patients (9 men, 14 women) aged 18 to 67 received 23 d-FRC-FPDs. The frameworks of the FPDs were unidirectional pre-impregnated glass fibers (ever Stick C&B). The retainers were inlay composite resin retainers (n1 = 19) and composite resin wings (n2 = 4). The FPD that used inlay retainers and composite resin wing retainers was called the hybrid design. The mean follow-up period was 4.91 years with 12-month check-ups performed by two independent operators. The survival rates of the glass fiber FPDs were determined. RESULTS Six-year survival rates for the two types of FPDs were 94.7% for the inlay retainer type versus 25% for the hybrid type, with a statistically significant difference (log-rank test χ2 (1) = 11.422, p = 0.001). The inlay retainers were functional, with only one patient with a fracture line in the connector held by the glass fibers. Kaplan-Meier survival curves were drawn to show the difference between the two types of retainers. CONCLUSIONS According to the results of this study, these long-term interim FRC-FPD were resistant enough to allow mastication, minimally invasive and also esthetic, with inlay composite retainers as the better solution.