A comparative study of 16 flavones was carried out using 4 experimental models: 1, hyperkinetic ventricular arrhythmias induced by reperfusion in rat isolated heart; 2, arrhythmias following coronary artery ligation-reperfusion in anaesthetized guinea-pig; 3, pytressine arrhythmias by coronary spasm in anaesthetized guinea-pig; and 4, anti-ischaemic activity using an ex vivo perfusion heart technique after coronary occlusion in guinea-pig. The structure effect relationships of flavone, 3-hydroxyflavone, 6-hydroxyflavone, 7-hydroxyflavone, 6,7-dihydroxyflavone, 7,8-dihydroxyflavone, apigenin, apiin, diosmin, 5-hydroxyflavone, luteolin, luteolin glycoside, orientin, pratol, rhoifolin, vitexin, tested as antiarrhythmic and anti-ischaemic agents were compared to lidocaine and verapamil at equimolar doses. The results obtained demonstrated that most of these compounds exerted a protective effect against coronary-spasm and coronary-ligation induced ischaemic crisis, and against the ischaemic and the post-ischaemic arrhythmias. The potencies were found to be structurally dependent for the flavones tested.