MicroRNAs (miRNAs) are important gene expression regulators and are involved in a variety of pathogeneses such as cancers and autoimmune diseases. Signal transducers and activators of transcription (STAT), the principle signaling proteins of many cytokines and growth factors, play significant roles in regulating immune cell homeostasis, cell differentiation and cell functions. In this review we discussed the recent advances in interactions between STATs and miRs, with focus on their interaction during the promotion and inhibition of immue cells and tumor cells. MiR-STAT interaction is still a new area of study, and more effort is needed to elucidate miR-STAT mechanisms.