The aim of this study was to clarify the prognostic significance of P-wave terminal force in lead V₁ (PTFV₁) in patients with prior myocardial infarction (MI). We retrospectively examined 185 patients with prior MI. The primary end point was cardiac death or hospitalization for heart failure. Abnormal PTFV₁ was defined as PTFV₁ ≥ 40 mm × ms. During a follow-up period of 6.4 ± 2.9 years, 39 patients developed the primary end point. A Kaplan–Meier analysis showed a lower primary event-free rate in 79 patients with abnormal PTFV₁ than in 106 patients with normal PTFV₁ (P < 0.001). When we classified 79 patients with abnormal PTFV₁ into 31 with a purely negative P wave in lead V₁ and 48 with a biphasic negative P wave in lead V₁, the primary event-free rate did not differ between the two groups of patients. A multivariate Cox regression analysis selected age (hazard ratio (HR) 1.09, 95 % confidence interval (CI) 1.04–1.14, P < 0.001), multivessel coronary disease (HR 2.33, 95 % CI 1.02–5.28, P = 0.04), and abnormal PTFV₁ (HR 2.72, 95 % CI 1.24–5.99, P = 0.01) as independent predictors of the primary end point. In conclusion, abnormal PTFV₁ is an independent predictor of cardiac death or hospitalization for heart failure in patients with prior MI. The analysis of P waves in lead V₁ should provide useful prognostic information in patients with prior MI.