The effect of various Calcium Entry Blockers (CEBs; nifedipine, flunarizine, diltiazem, verapamil) on ethanol-induced bronchoconstriction was studied in normal healthy volunteers. Nifedipine and diltiazem inhibited the bronchoconstriction and verapamil and flunarizine had no effect. The data favour the general hypothesis of differential tissue sensitivity to the various CEBs. The activity of CEBs on bronchomotor tone may be of therapeutic value in patients in whom bronchodilator activity is recommended in addition to the cardiovascular action.