Mesalazine is an aminosalicillic derivative considered as a safe alternative to the relative frequency (5-55%) of adverse effects observed with sulfasalazine. The well known hepatoxicity associated with sulfasalazine and attributed to its sulfamidic fraction is limited to few cases described in the treatment with mesalazine. We herein present a new case of hepatoxicity by mesalazine in a patient with lymphocytic colitis. The possible pathogenic mechanism is also commented upon.