Naïve CD4 T cells differentiate to a distinct subset to mount specific inflammatory responses while minimizing self-reactivity. Recent work has identified that an imbalance between T helper (T) 17 cell and regulatory T (Treg) cells is involved in the pathophysiology of tumor immune responses. The factors that modulate the development of T17 and Treg cells are variable but still unclear. Peritoneal adhesion is a common complication of surgery and peritonitis, which can lead to abdominal pain, intestinal obstruction, and infertility. In this study, we examined the role of peritoneal adhesions in development of T17 and Treg cells and discovered that adhesions reduced proliferation of T17 cells and promoted the Tregs. in particular we found that adhesion modulated the activity of signal transducers and activators of transcription (STAT) 5 which was critical for the development of T17 and Treg cells.