Colonic diverticulitis shows a high recurrence rate, but the role of faecal markers in predicting recurrence is unknown. The aim of this study was to investigate the role of faecal calprotectin (FC) in predicting recurrence of diverticulitis.A prospective cohort study was performed on 54 patients suffering from acute uncomplicated diverticulitis (AUD) diagnosed by computerized tomography (CT). After remission, patients underwent to clinical follow-up every 2 months. After remission and during the follow-up, FC was analysed. Recurrence of diverticulitis was defined as return to our observation due to left lower-quadrant pain with or without other symptoms (e.g. fever), associated with leucocytosis and/or increased C-reactive protein (CRP). Presence of diverticulitis was confirmed by means of CT.The mean follow-up was 20 months (range 12-24 months). Forty-eight patients were available for the final evaluation, and six patients were lost to follow-up. During follow-up, increased FC was detected in 17 (35.4 %) patients and diverticulitis recurred in eight patients (16.7 %). Diverticulitis recurred in eight (16.7 %) patients: seven (87.5 %) patients showed increased FC during the follow-up, and only one (12.5 %) patient with recurrent diverticulitis did not show increased FC. Diverticulitis recurrence was strictly related to the presence of abnormal FC test during follow-up.In the present prospective study, increased FC was found to be predictive of diverticulitis recurrence.