Objective. Pouchitis is a common and troublesome condition in patients operat ed on with ileal- pouch- anal- anastomosis (IPAA). A disturbed microecology i n the pouch has been suggested as one possible explanation. In a previous double - blind, randomized, controlled study we demonstrated clinical improvement of s ymptoms in patients with ulcerative colitis (UC) operated on with IPAA, during i ntervention with live probiotic microbes Lactobacilli and Bifidobacteriae. The a im of the present study was to confirm our previous results in a much larger mat erial, including clinical symptoms, faecal flora and endoscopic evaluation, and to compare the results in UC/IPAA patients with those of patients with familial adenomatous polyposis (FAP) with IPAA and UC patients with ileorectal anastomosi s (IRA). Material and methods. Five hundred millilitres of a fermented milk prod uct (Cultura) containing live lactobacilli (La- 5) and bifidobacteriae (Bb- 12 ) was given daily for 4 weeks to 51 UC patients and 10 patients with FAP, operat ed on with IPAA, and six UC patients operated on for IRA. Stool samples were cul tured for examination of lactobacilli, bifidobacteriae, fungi and pH before, dur ing and after intervention. Before, during and after intervention, endoscopic ev aluation was performed. Categorized symptomatology was examined prospectively using diary cards in addition to an interview, before and on the last day of intervention. Results. The number of l actobacilli and bifidobacteriae increased significantly during intervention in t he UC patients operated on with IPAA and remained significantly increased one we ek after intervention. Involuntary defecation, leakage, abdominal cramps and the need for napkins (category I), faecal number and consistency (category II) and mucus and urge to evacuate stools (category III) were significantly decreased du ring intervention in the UC/IPAA group. In the FAP group there was a significant decrease in faecal leakage, abdominal cramps and use of napkins (category I) du ring intervention. The median endoscopic score of inflammation was significantly decreased during intervention in the UC/IPAA patients. Blood tests, faecal fung i and faecal pH did not change significantly during intervention. Conclusions. R esults of this extended study, showing an effect of probiotics on symptoms and e ndoscopic inflammation in UC patients operated on with IPAA confirmour previousl y reported effect of probiotics on clinical symptoms and endoscopic score in a s maller, double- blind, randomized, controlled study. The significantly higher r esponse to probiotics in families with increased risk of IBD will have to be rep eated in future studies. Objective: Pouchitis is a common and troublesome condition in patients operat ed on with ileal-pouch-anal-anastomosis (IPAA). A disturbed microecology in the pouch has been suggested as one possible answer. In a previous double - blind, randomized, controlled study we demonstrated clinical improvement of s ymptoms in patients with ulcerative colitis (UC) operated on with IPAA, during i ntervention with live probiotic microbes Lactobacilli and Bifidobacteriae. The a im of the present study was to confirm our previous results in a much larger mat erial, including clinical symptoms, faecal flora and endoscopic evaluation, and to compare the results in UC / IPAA patients with those of patients with familial adenomatous polyposis (FAP) with IPAA and UC patients with ileorectal anastomosis (IRA). Material and methods. Five hundred millilitres of a fermented milk prod uct (Cultura) containing live lactobacilli (La-5) and bifidobacteriae (Bb-12) was given daily for 4 weeks to 51 UC patients and 10 patients with FAP, operat ed on with IPAA, and six UC patients operated on for IRA. Stool samples were cul tured for examination of lactobacilli, bifidobacteriae, fungi and pH before, dur ing and after intervention. Before, during and after intervention, endoscopic ev aluation was performed. Categorized symptomatology was examined prospectively using diary cards in addition to an interview, before and on the last day of intervention. Results. The number of l actobacilli and bifidobacteriae increased significantly during intervention in he UC patients operated on with IPAA and RESecutely increased one week after intervention. Involuntary defecation, leakage, abdominal cramps and the need for napkins (category I), faecal number and consistency (category II) and mucus and urge to evacuate stools (category III) were significantly decreased du ring intervention in the UC / IPAA group. In the FAP group there was a significant decrease in faecal leakage, abdominalcramps and use of napkins (category I) du ring intervention. The median endoscopic score of inflammation was significantly less during intervention in the UC / IPAA patients. Blood tests, faecal fungi and faecal pH did not change significantly during intervention. Conclusions. R esults of this extended study, showing an effect of probiotics on symptoms and e oscopic ndoscopic inflammation in UC patients operated with IPAA confirm next previous reported results of probiotics on clinical symptoms and endoscopic score in as maller, double-blind, randomized, controlled study. The significantly higher r esponse to probiotics in families with increased risk of IBD will have to be rep eated in future studies.