Objective - To assess the risk of atrial fibrillation (AF) recurrence requiring hospitalisation or its transition to long-lasting AF in patients with earlier or present AF from the clinical characteristics, the duration of AF-disease, and the signal-averaged P wave duration (SAPWD). Design -We studied 111 consecutive patients (40 women; median age 65 years, range 30-85 years) with earlier or present AF. The SAPWD was measured on inclusion; the follow-up median follow-up time was 184 days (range 171-437). Endpoints were hospitalisation due to recurrent AF or transition to AF lasting longer than two days. Results -During follow-up 5 patients died, 33 patients were hospitalised with AF, and 9 patients developed long-lasting AF. Multiple logistic regression analysis showed three risk factors of interest: history of hypertension, OR=3.67 (95% CI 1.61 to 8.37), duration of AF disease longer than two years, OR=3.22 (95% CI 1.31 to 7.86), and non-significantly prolonged SAPWD above 140 ms, OR=1.87 (95% CI 0.60 to 5.82). The probability of relapse in patients without risk factors was 9%, with one risk factor 16-27%, with two risk factors 37-54%, and with three risk factors 74% (p=0.0005). Conclusions -Hypertension and long history of AF disease were associated with an increased risk of AF-relapse.