We present a patient with psoriasis who developed exfoliative dermatitis with concomitant fever, malaise and liver enzyme elevations, two days after the introduction of the new calcium antagonist diltiazem. The symptoms rapidly resolved after discontinuation of diltiazem and treatment with prednisone. Three years previously, this patient developed a similar reaction after 12 days of treatment with chloroquine. Diltiazem and chloroquine have a structural resemblance, which suggests that cross-reactions between these drugs may occur.