The aim of this study was to evaluate the influence of monomer content on fracture toughness (K Ic ) before and after ethanol solution storage, flexural properties and degree of conversion (DC) of bisphenol A glycidyl methacrylate (Bis-GMA) co-polymers.Five formulations were tested, containing Bis-GMA (B) combined with TEGDMA (T), UDMA (U) or Bis-EMA (E), as follows (in mol%): 30B:70T; 30B:35T:35U; 30B:70U; 30B:35T:35E; 30B:70E. Bimodal filler was introduced at 80wt%. Single-edge notched beams for fracture toughness (FT, 25mm×5mm×2.5mm, a/w=0.5, n=20) and 10mm×2mm×1mm beams for flexural strength (FS) and modulus (FM) determination (10mm×2mm×1mm, n=10) were built and then stored in distilled water for 24h at 37°C. All FS/FM beams and half of the FT specimens were immediately submitted to three-point bending test. The remaining FT specimens were stored in a 75%ethanol/25%water (v/v) solution for 3 months prior to testing. DC was determined with FT-Raman spectroscopy in fragments of both FT and FS/FM specimens at 24h. Data were submitted to one-way ANOVA/Tukey test (α=5%).The 30B:70T composite presented the highest K Ic value (in MPam 1/2 ) at 24h (1.3±0.4), statistically similar to 30B:35T:35U and 30B:70U, while 30B:70E presented the lowest value (0.5±0.1). After ethanol storage, reductions in K Ic ranged from 33 to 72%. The 30B:70E material presented the lowest reduction in FT and 30B:70U, the highest. DC was similar among groups (69–73%), except for 30B:70U (52±4%, p<0.001). 30B:70U and 30B:35T:35U presented the highest FS (125±21 and 122±14MPa, respectively), statistically different from 30B:70T or 30B:70E (92±20 and 94±16MPa, respectively). Composites containing UDMA or Bis-EMA associated with Bis-GMA presented similar FM, statistically lower than 30B:35T:35U.Composites formulated with Bis-GMA:TEGDMA:UDMA presented the best compromise between conversion and mechanical properties.