*Objective*: Evaluate monomer elution from bulk-fill and conventional resin-composites stored in various media using HPLC for up to 3 months. *Methods*: Tested six bulk-fill and eight conventional resin-composites by immersing cylindrical samples in different solutions and analyzing them with HPLC. *Results*: Detected TEGDMA, DEGDMA, UDMA, and TCD-DI-HEA in water and artificial saliva. Higher elution in 70% E/W, especially from UDMA-BisEMA composites. Elution rates varied based on monomer type and molecular weight. *Significance*: Bulk-fill resin-composites exhibit elution levels similar to conventional materials. Elution is influenced by monomer hydrophobicity and resin-matrix characteristics.