The clinical pattern and physiological abnormalities in solitary rectal ulcer syndrome (SRUS) occurring in Singapore, were investigated. Since April 1989, 25 patients have presented with histologically proven SRUS. There were 13 males and 12 females (20 Chinese, 4 Malay and 1 Indian) with a mean age of 47.5 (+/- 3.1) years. Ninety-six per cent presented with rectal bleeding, 92% strained at stools, 40% had mucus discharge, 40% felt incomplete defecation and 32% digitated to defecate. Four had previous haemorrhoidectomies that did not cure their symptoms. The lesions were at a mean 6.8 (+/- 0.5) cm above the anal verge, usually anteriorly (64%) but one was circumferential. Anorectal physiology performed on 14 patients was compared with 13 age and gender matched normal controls. The measured mean resting perineum level in SRUS (1.4 +/- 0.3 cm) was significantly lower than in normals (P < 0.01). The mean anal electrosensory threshold (2.5 +/- 0.52 mV) was also significantly higher than in the controls (P < 0.05). Fifteen patients were successfully treated with a high fibre diet and avoidance of straining. Three patients required surgery and the most recent seven patients have responded well to biofeedback treatment. Awareness of this uncommon anorectal condition is necessary for early diagnosis and appropriate management. The physiological findings support a pelvic straining pathophysiology resulting in perineal descent, with less sensitive rectal mucosa prolapsing into, and raising, the anal canal electrosensory threshold. Treatment strategies aimed at correcting the straining have usually been successful.