Chronic constipation may be secondary to dietary, metabolic or neurological causes such as cerebrovascular accidents (CVA). In certain patients, the cause is unknown (primary idiopathic constipation [PIC]). This study compared the anorectal physiological parameters of 15 PIC patients (all females; median age 40, range 32-48 years) with 7 CVA patients (M:F = 6:1; median age 58, range 51-67 years), to observe the influence of cerebral factors on the anorectal physiology of constipation. Twenty-five normal subjects (M:F = 13:12; median age 47, range 43-50 years) acted as controls. Transit marker studies showed decreased passage in both groups, but 9 of the PIC patients had a diffuse pattern (slow transit constipation [STC]) and 6 had a pelvic outlet obstruction pattern (PO). The CVA patients had a diffuse pattern of delayed transit. Rectal sensation was significantly impaired in STC (P < 0.05) but not in PO or CVA. Electromyographic evidence of paradoxical puborectalis contractions was significantly more common in PO only (P < 0.05). Therefore, CVA patients had a different anorectal physiological pattern of constipation from PIC patients.