The purpose of this study was to determine possible temporal changes of stroke incidence in a European community. All cases of first-ever stroke (n = 927) were prospectively recorded in the municipality of Frederiksberg, Denmark, in the two periods 1972-1974 and 1989-1990. Complete case ascertainment was ensured by registration of both hospitalized and nonhospitalized patients. Death certificates were also scrutinized. The annual stroke incidence rate per 1000 increased by 18% from 2.6 in 1972-1974, to 3.1 in 1989-1990 (p < 0.01). This increase was due solely to a 42% increase in men, for whom stroke incidence rose from 2.1 to 3.0 (p < 0.0005). Incidence was unchanged in women, 3.0 and 3.1 respectively. In the second study period 85% had CT or necropsy; 91% had cerebral infarction; 8% had intracerebral haemorrhage and 1% had subarachnoid haemorrhage. In a period when decline in stroke incidence has stopped in USA and has continued in Japan, a marked increase in stroke incidence in European men was observed.