A report of a follow up study on a selected male population aged 50-59 from one of the central districts of Moscow is presented. The initial check-up found ischaemic heart disease (IHD) in 18.4% of cases, and 61/2 years later in 27.7% (p less than 0.01). The frequency of new cases of IHD appearing was 17.6%, in older age group (55-59) it was 2.8% higher, than in the younger group (50-54). In the older male group during the observation period death rate from IHD was encountered more frequently (6.1%), than in the younger group (1.6%). The number of new cases of myocardial infarction found during the second investigation, and deaths from acute coronary insufficiency in both age groups was practically the same: 8.2% among the total population. General number of new cases of IHD in 61/2 years, determined with mortality from IHD was 18.4%, or 2.8% per year. The stability of the more severe manifestations of IHD is shown. It is noted that atypical forms of angina pectoris and "doubtful" ischaemic changes on ECG may be regarded as "precursors" of IHD and persons with such signs require further follow up.