Objective Even if intestinal absorption is not directly impaired ulcerative colitis (UC) deserves important metabolic implications. In fact, chronic inflammation and accelerated intestinal transit may significantly influence lipid metabolism. Restorative proctocolectomy (RPC) usually obtains the resolution of inflammatory process but the accelerated transit may persist. The aim of this prospective study was to evaluate the changes of the metabolism of circulating and storage lipids of UC patients after RPC. Method Fifteen patients who underwent RPC for UC between December 2004 and April 2006 were enrolled. Disease activity, diet, inflammatory parameters, lipid profile and composition of fatty acids (FA) of serum phospholipids were assessed at RPC and at ileostomy closure. In 9 patients at RPC, and in 10 at the ileostomy closure, FA composition of phospholipids of subcutaneous adipose tissue were also evaluated. Fifteen sex-and-age matched healthy subjects were enrolled as controls. Data were expressed as median (range) and Wilcoxon paired- and Mann-Whitney U tests were used.Results The median interval between RPC and ileostomy closure was 6 (2-9) months. In UC patients total cholesterol was significantly lower than in healthy subjects at RPC and at ileostomy closure. During that interval the inflammatory parameters improved as well as lipid profile (median HDL-cholesterol: from 43 (19-65) to 56 (25-84) mg/dl, p<0.01; median LDL-cholesterol: from 100 (26-160) to 52 (24-139) mg/dl, p=0.01). At ileostomy closure serum arachidonic acid and docosaesaenoic acid levels were increased compared to levels at RPC (p=0.04 and p=0.05, respectively), while serum oleic acid level was decreased (p=0.02). No significant alteration in serum n-3 FA precursors was observed in UC patients in the interval between RPC and ileostomy closure. On the contrary 22:6 n3 appeared to be lower in UC patients at ileostomy closure compared to healthy controls (p<0.01). No significant differences in the composition of FA of subcutaneous adipose tissue were observed between RPC and ileostomy closure. Conclusion The increase of serum percentage of arachidonic acid after RCP might be explained by a lower utilization for inflammatory process. The observed reduction of LDL cholesterol could be an index of malabsorption and was probably due to the persistency of an accelerated transit and to the exclusion of the terminal ileum caused by the covering ileostomy.