Objective—Premature ventricular contractions (PVCs) were observed among patients with heart diseases. It has been suggested that the sporadic left bundle branch block (LBBB) pattern of PVCs observed in healthy subjects has no relevance to heart diseases and the presence of this type of PVC was not associated with a poor prognosis. The aim of this study is to present and evaluate the relationship between PVC patterns on routine electrocardiography (ECG) and heart diseases. Methods: The subjects examined were 201 employees from one company (male 192, female 9) with PVCs (Lown grading classification 0 or 1). The patterns of PVCs were classified into the following four categories regarding the bundle branch block pattern and electrical axis deviation: 1) the LBBB pattern without axis deviation (135 subjects), 2) the LBBB pattern with left axis deviation (29 subjects), 3) the right bundle branch block (RBBB) pattern without axis deviation (22 subjects) and 4) the RBBB pattern with left axis deviation (15 subjects). Results—The presence of subjective symptoms was not significant in each category. Prevalence of heart disease was 1) 14 (10.4%), 2) 10 (34.5%), 3) 9 (40.9%) and 4) 7 (46.7%). The subjects with the LBBB pattern without axis deviation had a lower incidence of having heart disease than subjects with other PVC patterns (p<0.05). In addition, similar findings applied to the observations in asymptomatic subjects. Conclusion—It is suggested that the population without heart disease primarily has the PVCs of the LBBB pattern without axis deviation and the analysis of the PVC patterns (bundle branch block pattern) and of electrical axis deviation in routine ECG at a routine health examination is useful for diagnosing heart disease.