Observations on tocolysis draw the obstetrician's attention to need to watch carefully maternal cardiac function before, during and after labour. In the light of recent experimental pharmacological and clinical observations the authors describe successively the physiology and the physiopathology of cardiac lesions brought about by beta-mimetics as well as the means available to prevent disseminated cardiac muscle necrosis. Clinical observations and maternal and fetal secondary effects of beta-mimetics are thus reviewed. In conclusion the authors describe their way of preventing cardiac muscle necrosis.