We describe a case of an Erdheim-Chester disease patient. First line chemotherapy treatment with 2-chlorodeoxyadenosine did not reduce fluorodeoxyglucose accumulation in pathological lesions. The patient had continuously increased CRP values of 17-20 mg/l. The disease continued to cause subfebrile temperatures and significant fatigue that made the patient to spend most of the daytime in bed. To manage the permanently increased inflammation markers, we decided to start treatment with anakinra, successfully used in some other autoinflammatory diseases (e.g. Schnitzler syndrome). We have now been able to evaluate the first 6 months of treatment. Daily subcutaneous administration of anakinra (KineretTM 100 mg daily) led to normalization of CRP values, cessation of subfebrile temperatures and, importantly, significant reduction of fatigue. Time periods the patient was able to spend out of the bed increased significantly. Consequent to the reduced fatigue, the patient was able to perform basic household tasks he was unable to undertake without treatment. After 3 months of treatment, fatigue of the same intensity returned following a short interruption of therapy. The CRP values went up again to 12 mg/l. CRP value returned back to norm and fatigue ceased after re-initiation of daily Kineret injections. Objective treatment response was assessed by measuring the degree of fluorodeoxyglucose accumulation in pathological bone lesions. PET-CT was performed before and 3 and 6 months after anakinra initiation. Intensity of accumulation did not change significantly after the first 3 months of therapy but decreased after 6 month therapy. Follow up CT of abdominal cavity was performed at the end of the 6th month of treatment. Presented CT images from before and 6 months after the treatment evidence an obvious reduction in fibroid changes in the retroperitoneum. Daily administration of anakinra to a patient with active Erdheim-Chester disease significantly reduced intensity of fatigue and improved quality of life, led to a reduction in inflammatory markers and regression in retroperitoneal fibrotization.