Background Scant data exist on incidence rates, correlates, and prognosis of electrocardiographic P-wave abnormalities in the general population. Methods We recorded ECG and measured conventional cardiovascular risk factors in 5667 Finns who were followed up for incident atrial fibrillation (AF). We obtained repeat ECGs from 3089 individuals 11 years later. Results The incidence rates of prolonged P-wave duration, abnormal P terminal force (PTF), left P-wave axis deviation, and right P-wave axis deviation were 16.0%, 7.4%, 3.4%, and 2.2%, respectively. Older age and higher BMI were associated with incident prolonged P-wave duration and abnormal PTF (P ≤ 0.01). Higher blood pressure was associated with incident prolonged P-wave duration and right P-wave axis deviation (P ≤ 0.01). During follow-up, only prolonged P-wave duration predicted AF (multivariable-adjusted hazard ratio, 1.38; P = 0.001). Conclusions Modifiable risk factors associate with P-wave abnormalities that are common and may represent intermediate steps of atrial cardiomyopathy on a pathway leading to AF.