Three-hundred and ninety-four 68-year-old men, representing 60.3% of a cohort of men born in 1914, were examined with ambulatory ECG during 24 h in 1982-83. Ninety-eight (24.8%) men had one or more episodes of ischaemic type ST segment depression (greater than or equal to 0.10 mV), 79 of whom had no history of previous ischaemic heart disease (IHD). During 63 months follow-up, 17 of the 98 suffered a cardiac event, i.e. fatal or non-fatal myocardial infarction (MI) or death due to chronic IHD. The objective of this study was to assess the influence of psychosocial factors, such as social network and social support, on cardiac event rate in men with ischaemic ST segment depression. A higher risk was found among men with little material and informational support (i.e. access to practical services and material resources and access to guidance, advice and information (crude relative risk 4.8; 95% CI; 1.6-14.8) and men with low availability of emotional support (i.e. opportunity for care, encouragement of personal value and feelings of confidence and trust) (crude relative risk 4.3; 95% CI: 1.4-13.3). This association was independent of history of IHD and other known risk factors for myocardial infarction (MI).