Résumé : Circulating concentrations of leucocyte elastase were measured in 20 adult patients undergoing cardiopulmonary bypass (CPB) with a flat-sheet membrane oxygenator. Eight patients (group I) received the calcium channel blocker, nifedipine (9μg/kg/h), during CPB and 2g methylprednisolone before CPB. Eight patients (group II) received methylprednisolone but not nifedipine infusion. Four patients (group III) received neither nifedipine nor methylprednisolone infusion. In all patients the bypass procedure was associated with elevation in elastase concentrations. Enzyme concentrations correlated with the duration of bypass (r = 0.7, p<0.01). Comparison between groups fails to demonstrate any significant effect of nifedipine infusion or methylprednisolone on elastase release. This study demonstrates moderate elastase release during CPB with a flat-sheet membrane oxygenator and fails to confirm inhibition of elastase release by nifedipine infusion during CPB.