Biological agents that act on IL-5 and eosinophils are used in the treatment of severe eosinophilic asthma. It is known that parasitic infections can be seen in dysfunctions of IL-5 and eosinophils. However, it has not yet been clearly clarified whether biological agents acting through IL-5 and eosinophils facilitate parasitic infections. A 67-year-old female patient, who was followed for 8 years with the diagnosis of severe eosinophilic asthma. Mepolizumab treatment was started because despite the treatments she received she had asthma exacerbations requiring systemic steroid use twice in 1 year and her eosinophil count was 620/µL. Twenty days after the second dose of mepolizumab treatment, the patient started to complain of dry itching. In the examinations, entamoeba histolytica cysts were seen along with abundant leukocytes and erythrocytes in every field (x400) in stool microscopy. The patient was started on metronidazole treatment by the infectious diseases clinic. With the treatment, the patient's itching complaint subsided and stool microscopic examination was found to be normal in the control visit. To our knowledge, this is the first case in the literature of an itching complaint due to Entamoeba histolytica infestation associated with the use of mepolizumab.