Interleukin-1 beta (IL-1β), also known as catabolin, is a cytokine of 269 amino acids (molecular weight 31 kDa). This cytokine is produced by activated macrophages as a proprotein, which is proteolytically processed to its active form by caspase-1. IL-1β is an important mediator of the inflammatory response and is involved in a variety of cellular activities, including cell proliferation, differentiation, and apoptosis. IL-1β is the most studied member of the IL-1 family of cytokines due to its role in mediating autoinflammatory diseases. Blood monocytes from patients with autoinflammatory syndromes release more processed IL-1β than cells from healthy subjects and thus likely account for the inflammation in these diseases.Neutralization of IL-1β results in rapid and sustained reduction in disease severity. Although some autoinflammatory diseases are due to gain-of-function mutations for caspase-1 activity, common diseases such as gout, type 2 diabetes, heart failure, recurrent pericarditis, rheumatoid arthritis, and smouldering myeloma are also responsive to IL-1β neutralization.