Due to the numerous biotechnological applications of laccase enzyme, it is essential to know the influence of different agents usually present in the natural environment on its enzymatic action, especially for in situ treatment technologies. In the present work, a simple and rapid method to determine the inhibitory or inducer effect of different compounds on laccase activity was developed. The compounds tested were copper-chelating agents and heavy metals. It was found that using syringaldazine as a substrate, all copper-chelating agents (except EDTA) highly inhibited laccase activity (around 100%) at an inhibitor concentration lower than 20 mM. Moreover, 40% of inhibition, which was detected at a concentration of 20 mM for both Cd(2+) and Cu(2+) increased with concentration until nearly complete inhibition at 80 mM.