TH 17 cells are recently recognized group T cells that have roles in clearance of microorganisms and induction of autoimmune diseases. These cells have distinct pathway of differentiation unlike to that of TH 1 and TH 2 cells.Different researches indicated the drivers and inhibitors involved in the differentiation of these novel cells.The effector function of interleukin 17 (IL-17), produced by these cells, has also been investigated. This short review provides an insight to TH 17 cells by compiling the outputs of different researches about the cell.