The efficiency of cysteine to remove mercury from sliced and minced shark was evaluated. Treatment with 0.5% cysteine at pH 2.0–2.5 and subsequent washing with sodium chloride (5%) failed to remove the mercury from the sliced shark. The efficiency of 0.5% cysteine at pH 7.0 in removing mercury from minced shark was 40–45% (dry material), obtained by two of the three methods studied. This removal rate was considered relatively low for it failed to attend to the practical proposal of decontaminating species of fish highly contaminated by mercury. The need for fuller understanding of the mechanisms involved in the removal of mercury by cysteine was also considered.