Atrial and ventricular arrhythmias have been reported with variable incidence in symptomatic patients with mitral valve prolapse (MVP). The role of clinical and echocardiographic parameters as predictors for arrhythmias still needs to be clarified. One hundred nineteen consecutive patients (56 women and 63 men, mean age 40 +/- 17 years) with echocardiographically diagnosed MVP were examined. A complete echocardiographic study (M-mode, two-dimensional, and Doppler) and 24-hour electrocardiographic monitoring were performed in all patients. Complex atrial arrhythmias (CAAs) included atrial couplets, atrial tachycardia, and paroxysmal or sustained atrial flutter or fibrillation. Complex ventricular arrhythmias (CVAs) included multiform ventricular premature contractions (VPCs), VPC couplets, and runs of three or more sequential VPCs (salves of ventricular tachycardia). The relation between complex arrhythmias and clinical parameters (age and gender) and echocardiographic parameters (left atrial and left ventricular dimensions, anterior mitral leaflet thickness [AMLT], and presence and severity of mitral regurgitation) was evaluated by multiple logistic regression analysis. CAA were present in 14% of patients and CVA in 30%. According to multiple logistic modeling, CAA correlated separately in the univariate analysis with age, presence of MR, and left ventricular and left atrial diameters; age was the only independent predictor (p < 0.001). CVA, in the univariate analysis, correlated with age, female gender, left ventricular end-diastolic diameter, and AMLT; only female gender and AMLT were independent predictors in the multivariate analysis (p < 0.01). The incidence of mitral regurgitation (59%) was higher than expected in a general population of MVP patients. In conclusion, in this population with MVP, age was independently correlated to CAA, whereas female gender and AMLT were independently related to CVA.