Beta-adrenoceptor blocking drugs reduce mortality by about 20% when used to treat patients in the first 1-3 years after a myocardial infarction. There is suggestive evidence of benefit, averaging about 14% reduction in mortality, when they are used acutely in the coronary crisis. The benefits of beta blockade in primary prevention in patients under treatment for hypertension are less clearly established. Two studies have suggested a benefit but only in non-smoking men, a third study has not confirmed the hypothesis. More evidence is needed. As there is little evidence of comparable benefit with other types of drug, e.g. calcium slow-channel inhibitors, it is reasonable to use beta-blocking drugs in male hypertensives (who should be encouraged to stop smoking in any case), unless there are specific contra-indications.