Eosinophilia occurs as a concomitant sign in multiple diseases of different etiology. Especially its occurrence in malignant diseases is still unknown. In three cases of primary sarcoma of the small intestine a constant eosinophilia is described. In one case this pronounced eosinophilia was present long before the final diagnose was made. The eosinophilic count was highest in the presence of clear symptoms of obstruction and normalized after surgical removal of the tumor. In one case a relapse was indicated by an increasing eosinophilic count. It is difficult to diagnose the sarcoma of the small intestine especially in its early stage because of the lack of typical symptoms. Concerning the described cases it is therefore pointed out, that in connection with undifferentiated abdominal complaints an obscure eosinophilia should be considered to be due to sarcomatous small bowel disease.