The fluoride release from dental composites has reported as an important factor in the inhibition of dental caries. The aim of this study was to determine the amount of fluoride release from two resin composites with different powder/liquid ratio. The experimental resin composites consisted of a resin system and inorganic filler based on quartz and sodium fluoride. Samples of resin composites were stored in bidistilled water and bidistilled water/TISAB buffer over 7 days. The results showed that resin composites released fluoride in time; water sorption and water solubility had a positive influence in this process. There was a little difference between fluoride release in bidistilled water and bidistilled water/TISAB buffer.