Constipation is a common complaint, but its clinical presentation varies with each individual. The aim of this study was to evaluate anorectal physiology in a prospective group of patients with chronic constipation. A total of 24 consecutive patients with constipation underwent solid-state anorectal manometry. Fifteen healthy controls were also studied. The anorectal parameters included resting and squeeze sphincter pressure, sensory thresholds in response to balloon distension, compliance of rectum, and rectoanal inhibitory reflex (RAIR). The rectal sensitivity for urge and pain did not differ between the groups, but the threshold volume for first sensation was higher in patients with constipation (p < 0.05). There was no group difference in the volume threshold for RAIR. However, the prevalence of impaired RAIR was higher in constipated patients. Anal pressure was lower in patients for maximal squeeze (p < 0.05). There was a positive correlation between the anal sphincter length and resting pressure in patients (r = 0.51, p = 0.03) and healthy controls (r = 0.72, p = 0.01). Constipated patients are characterized by impaired rectal sensitivity and decreased anal sphincter contractile pressure. Anorectal manometry is helpful for diagnosing anorectal dysfunction in patients with chronic constipation.