INTRODUCTION: Epidemiology data on constipation are not commonly available, particularly in Italy Here we review the prevalence and clinical features of constipated patients attending a tertiary referral Italian center. METHODS: Clinical data of patients attending our Coloproctology Unit in the last 15 years and complaining of constipation as the main clinical features were retrospectively analyzed. Rome-III criteria were adoptedto define constipation. RESULTS: 1041/11881 patients were affected by chronic constipation (8.8%), 376 had slow-transit constipation, 497 obstructed defecation and 168 both types of constipation. 76% of them were females. Patients distribution according to sex and age was Gaussian-like only in females. In the slow-transit group, constipation was idiopathic in 59.3% and secondary to other causes in 40.7% . In patients with anatomic obstructed defecation, rectocele and intussusceptions were the main findings, while pelvic floor dissynergia was the main finding in functional outlet obstruction, although more frequently all these components were associated. In 14.8% no apparent cause was identified. CONCLUSION: Constipation accounts for about 9% of patients attending a tertiary referral Colorectal Unit. Females were much more frequently affected in both types of constipation. Anatomic and functional defecatory disturbances are frequently associated, although in 15% no evident causes were identified.