Agranulocytosis is a disorder characterized by a severe decrease in the number of granulocytes in blood, that frequently occurs as an adverse reaction to some drugs. By now, there are no reports in literature of agranulocytosis caused by tumur necrosis factor-alpha blockers. We describe the case of a 20-year-old Caucasian male affected by enteropathic (Crohn's disease) spondyloarthropathy HLA B27 negative, successfully treated with infliximab. After the second infliximab infusion, he was found to have a severe transient neutropenia (0.5 x 10(9)/L). Routine serum chemistry and full blood cell count (apart from neutrophil count) were normal. Serology excluded an active infection. Bone marrow needle aspirate showed a normal trilineage differentiation. Autoantibody assessment showed negative ANA, anti-dsDNA, anti-ENA, and ANCA, but positive granulocyte-bound antibodies (GBA) and neutrophil-specific (CD 16+)-bound antibodies (anti-NA). Ten weeks after infliximab infusion, neutrophil count and GBA and anti-NA assay returned spontaneously within normal range and we observed the same progress after every successive infliximab infusion we performed. These data indicated that infliximab possibly triggered production of granulocyte and neutrophil autoantibodies with resultant autoimmune agranulocytosis.