Tumor necrosis factor (TNF is used synonymously with TNF-alpha) is a pleiotropic cytokine. The effects of TNF were first described in the last century, but the soluble factor was discovered in 1975. Now TNF is one of the most important cytokines investigated by scientists from different fields. This short review briefly summarizes the state of the art and adds the news of the last 2 years. The progress in the field of TNF is focussed on gene organization and transcription, gene polymorphism, biochemistry of TNF, TNF receptors and the biological role of TNF in autoimmune diseases, infectious diseases, transplantation, cancer and TNF functions on endothelial cells.