This study will investigate the correlation of fecal calprotectin (FC) values to quiescent ulcerative colitis and to disease activity (relapse) as assessed by clinical data and endoscopy.

The study is prospective with a longitudinal approach. About 200 patients will be followed every 3 to 12 months (at basal, 3, 6, 9 and 12 months alternating visits to telephone contacts) and subsequently for further 6 months in 3 different sites (competitive enrollment, 1site/country, Italy, France and Spain respectively). Fecal samples for immunoassays will be collected at follow up visits, stored frozen (-20°C) and sent to testing lab for their determination.

The following assessments are foreseen:

Clinical history and demography (screening), Proctosigmoidoscopy (basal), Hemochromo with WBC differential count, C-reactive protein (every 6 months from screening up to 12 months; relapse), Coagulation (screening) Specimen collection for fecal calprotectin determination (within 1-2 weeks from Informed Consent signature; for basal time point; every next 3 months from basal up to 12 months and at month 18; relapse), Coproculture for Salmonella, Shigella, E. Coli and Campylobacter (relapse), Pharmacological ongoing therapy, Mayo score (each time point; relapse)

Inclusion Criteria:

• Adults,18 years and older, either genders
• Subject previously diagnosed with left-sided colitis or pancolitis based on endoscopy and, if available, confirmed by histological examination of biopsy taken during endoscopy
• Subject in clinical and endoscopic remission. Remission will be documented by proctosigmoidoscopy.
• Subject who may receive maintenance therapy as per current medical practice, e.g. mesalazine, corticosteroids, azathioprine, anti-TNF
• Availability of stool specimen for basal time point
• Subject willing and able to sign, the approved Informed Consent Form for this project in accordance with international and national regulations
• Subject able to understand and follow study procedures

Exclusion Criteria:

• Any subject that does not meet the inclusion criteria
• Subject with microscopic colitis
• Subject with Crohn's disease
• Subject with limited proctitis
• Subject with severe chronic disease affecting the possibility to comply with the study protocol (i.e. severe cardiovascular disease, renal or liver failure, neurologic disease, hematological disease and mental disorder)
• Subject who is regularly taking oral anticoagulants
• Subject who is currently pregnant or lactating
• Subject unable or unwilling to subscribe informed consent
• Subject unable or unwilling to perform required study procedures