Seventeen patients with progressive systemic sclerosis (PSS) were evaluated with manometry for anorectal function, and an additional 36 age-matched normal subjects were collected as a control group. The study group had a significant decrement of maximum basal pressure (MBP), 42.6 +/- 27.0 mm Hg, in PSS as compared with the control group, 71.2 +/- 24.9 mm Hg (P = .0004). The difference in the functional length (FL) of the anal canal, PSS:control = 2.4 +/- 1.0 cm:3.7 +/- 0.5 cm (P = .0001); the volume of first defecating sensation, PSS:control = 66.3 +/- 35.2 ml:125.1 +/- 43.8 ml; the voluntary component, the difference between maximum squeeze pressure (MSP) and MBP, PSS:control = 116.6 +/- 73.6 mm Hg:61.8 +/- 35.9 mm Hg (P = .0087), were also found to be statistically significant. Nevertheless, the MSP and maximal tolerable capacity (Vmax) showed no difference in these two groups (MSP, PSS:control = 159.3 +/- 88.1 mm Hg:132.9 +/- 44.9 mm Hg, P = .259), (Vmax, PSS:control = 193.1 +/- 67.7 ml:230.0 +/- 60.9 ml, P = .0526). Twelve (71 percent) of 17 patients did not have rectoanal inhibitory reflex, and paradoxical contraction during rectal balloon inflation was noted in ten patients. Nine patients had different degrees of anal incontinence and abnormal anometric profiles were found in six of eight asymptomatic patients. Therefore, only two patients (12 percent) had neither symptoms nor anometric evidence of anorectal involvement in PSS. Two patients with long-standing disease received posterior anal repair for stool incontinence, the postoperative results were satisfactory both subjectively and objectively. The average MBP increased from 0 to 20 mm Hg, average FL from 0 to 1.5 cm. Patients complained less frequently about stool incontinence or soiling, and their daily life is now more comfortable. The analysis indicates that anorectal function in PSS is affected much more frequently and earlier than thought. Anorectal manometry can be used as an adjuvant in diagnosing controversial cases. Once anal incontinence occurs, posterior anal repair can achieve good results after six months of follow-up.