In a survey, 19222 males and females aged 12-64 answered a question about sudden changes of heart rate or rhythm during the preceding year. The prevalence of reported arrhythmia was 12.4% in males and 17.2% in females. Multiple logistic regression was performed with self-reported arrhythmia as the dependent variable and psychological, lifestyle, and coronary risk factors as independent variables. The highest odds ratio for reported arrhythmia concerned poor compared with excellent health status; 3.86 in males and 2.98 in females. The relative risk for reported arrhythmia according to frequency of physician consultations was 2.28 in males and 1.70 in females, and odds ratios in both sexes were significant for psychological problems and smoking. The findings suggest that attention should be paid to the psychological conditions and lifestyle of patients who report irregular heartbeats. Self-reported arrhythmia may be a minor problem from a clinical point of view, but we still do not know its prognostic implications. Further work is necessary to determine the predictive strength of self reported arrhythmia for morbidity and mortality.