Objective. Hyper-IgD syndrome(HIDS) is a rare autosomal recessive disease characterized by recurrent fever, lymphadenopathy, diarrhoea, abdominal pain, headache, arthralgia and skin rash. Abdominal symptomatology may mimic inflammatory bowel disease. We report on four patients with HIDS who had been previously investigated for Crohn’s disease (CD). The levels of IgD were measured in a series of patients with CD to evaluate the specificity of this assay in the differential diagnosis between the two conditions. Material and methods. Diagnosis of HIDS was based on clinical criteria as well as immunological or genetic data. IgD levels were measured in the four subjects affected by HIDS, in 59 patients with CD and in a group of 160 healthy controls. Result. All patients underwent a variety of gastroenterological investigations because inflammatory bowel disease was suspected. Ultrasonography was pathologic in all the patients, showing enlargement of mesenteric lymph nodes. Abdominal leucocyte scintigraphy displayed diffuse signals of mild to moderate degree. IgD and IgA levels were elevated in three out of four patients. No difference in IgD values was found in CD patients as compared to the control group. Conclusions. Gastrointestinal complaints associated with recurrent fever and mesenteric adenopathy warrant genetic investigation for HIDS, in order to avoid unnecessary invasive investigations and treatment. Objectives Hyper-IgD syndrome (HIDS) is a rare autosomal recessive disease characterized by recurrent fever, lymphadenopathy, diarrhea, abdominal pain, headache, arthralgia and skin rash. Abdominal symptomatology may mimic inflammatory bowel disease. We report on four patients with HIDS who had been previously investigated for Crohn’s disease (CD). The levels of IgD were measured in a series of patients with CD to evaluate the specificity of this assay in the differential diagnosis between the two conditions. clinical criteria as well as immunological or genetic data. IgD levels were measured in the four subjects affected by HIDS, in 59 patients with CD and in a group of 160 healthy controls. Result. All patients underwent a variety of gastroenterological investigations because inflammatory bowel disease was suspected. Ultrasonography was pathologic in all the patients, showing enlargement of mesenteric lymph nodes. Abdominal leucocy No difference in IgD values ​​was found in CD patients as compared to the control group. Conclusions. Gastrointestinal complaints associated with recurrent fever and mesenteric adenopathy warrant genetic investigation for HIDS, in order to avoid unnecessary invasive investigations and treatment.