Abstract: In order to investigate the chloramphenicol residues in commercially available shellfish and to assess their exposure, we collected 300 shellfish samples which were determined by LC-MS/MS and analyzed by @risk software using Monte Carlo method. The daily intake and estimated dietary exposure were simulated, and the margins of exposure were calculated. The results show that 33 samples were determined to have chloramphenicol residues in 2015. The MOE value of the general population was 15 361, presenting a medium risk (according to the evaluation criteria of the Canadian Ministry of Health). The MOE value of the high exposure population was 5 208, also presenting a medium risk. In 2016, three samples were determined to have chloramphenicol residues. The MOE value of the general population was 10 3627, presenting a medium risk. The MOE value of the high exposure population was 34 722, presenting a medium risk. In 2017, no samples were determined to have chloramphenicol residues, presenting no risk.