The role of serum autoantibodies, soluble adhesion molecules, plasma and mucosal cytokines were studied following surgery for ulcerative colitis (UC). A high prevalence of ANCA was found in UC but not in Crohn’s disease. ANCA positive UC sera were found to recognise a variety of antigens, namely lactoferrin, cathepsin G, enolase and elastase. Confocal microscopy revealed maximum immunofluorescence for P-ANCA to emanate from the intranuclear and not the extra-(peri) nuclear portion of the neutrophil, as currently believed. AECA, like ANCA, are also found in UC, suggesting immunological similarities with systemic vasculitis. Perhaps, UC represents a gut limited vasculitis. Persistance of ANCA, AECA, anti-EPI and antitropomyosin antibodies in the sera, several years following total colectomy, suggests that immunological mechanisms are not halted, by total colectomy. Soluble intercellular cell adhesion molecules, ICAM-1 and E-Selectin, but not VCAM-1, were found to be useful markers of disease activity in UC. Plasma levels of cytokines do not reflect disease activity, however, there is similar quantitative expression of pro-inflammatory cytokines by isolated mucosal mononuclear cells in both active UC and pouchitis, but not in nonspecific proctitis, which seems to suggest that pouchitis is not merely a complication of ileoanal pouch surgery but, that it represents reactivation of UC in ileal mucosa, which has undergone villous atrophy and colonic metaplasia.