Snoring is a prerequisite for obstructive sleep apnoea (OSA) and is known to run in families. Recent studies have provided sufficient evidence for a familial predisposition to OSA. In our study, 492 monozygotic and 284 dizygotic twins were contacted by telephone and asked to attend an interview which included questions of life habits, medical history, sleep habits and disorders, with particular emphasis on snoring. Our study showed that the probandwise concordance rate for habitual snoring was higher in monozygotic twins than in dizygotic ones, but the difference was not significant. The comparison of concordant pairs for habitual snoring vs. concordant pairs for non-snoring confirmed that habitual snoring is significantly associated with older age, male gender, higher body mass index (BMI), smoking and respiratory diseases. The multivariate analysis in the discordant groups confirmed that BMI is more strongly associated to habitual snoring in dizygotic twins than in the monozygotic ones. Our logistic analysis showed that other variables, such as smoking and respiratory diseases, are associated with habitual snoring in dizygotic pairs, but not in monozygotic ones. These findings suggest a genetic predisposition to habitual snoring.