We studied the physiological features of patients with complete rectal prolapse and different degrees of solitary rectal ulcer syndrome to determine whether these conditions are likely to form part of the same disorder. 52 solitary rectal ulcer patients (median age 31, 40 females), and 15 complete rectal prolapse patients (median age 31, 12 females) were studied. Solitary rectal ulcer patients were divided into 3 groups, based on the extent of accompanying rectal prolapse (no prolapse, internal prolapse, or external prolapse). Both solitary rectal ulcer patients without prolapse and with internal prolapse had significantly higher maximum anal resting (p < 0.01 for both groups) and squeeze pressure (p < 0.05 for both groups) than complete rectal prolapse patients. In contrast, solitary rectal ulcer patients having external prolapse were similar to those with complete rectal prolapse. Solitary rectal ulcer patients without rectal prolapse had significantly decreased anal and rectal electrosensitivity (p < 0.01 for both) when compared to healthy control subjects. Solitary rectal ulcer patients therefore have a spectrum of clinical and physiological features--this condition may comprise a range of different disease entities. The findings also suggest a different underlying aetiopathophysiology of solitary rectal ulcer from that of complete rectal prolapse.