Purpose: to (1) examine the occurrence and concentrations of aPS/PT and aPL in inflammatory bowel disease (IBD) patients at the beginning of and during anti-TNFalpha therapy with infliximab; (2) investigate the link of the aPS/PT and aPL presence with antibodies to infliximab (ATI) formation; and (3) examine possible clinical consequences of aPS/PT and/or aPL positivity in IBD patients.