Inhibitory molecules against IL-1 have been described from a variety of sources such as febrile patient urine, monocyte/macrophase cell line, and virus infected monocyte/macrophage. In this review, we introduce the IL-1 inhibitor from different sources and discuss the characteristics of IL-1 inhibitor (IL-1 receptor antagonist) from monocyte. We may be to consider whether the IL-1 inhibitor can be used as a therapeutic agent against IL-1 induced diseases.