3’-end cleavage and subsequent polyadenylation are critical steps in mRNA maturation. The precise location where cleavage occurs (referred to as poly(A) site) is determined by a tripartite mechanism in which a A(A/U)UAAA hexamer, GU rich downstream element and UGUA upstream element are recognized by the cleavage and polyadenylation factor (CPSF), cleavage stimulation factor (CstF) and cleavage factor I_m (CFIm), respectively. CFI_m is composed of a smaller 25 kDa subunit (CFI_m25) and a larger 59, 68 or 72 kDa subunit. CFIm68 interacts with CFI_m25 through its N-terminal RNA recognition motif (RRM). We recently solved the crystal structures of CFI_m25 bound to RNA and of a complex of CFIm25, the RRM domain of CFI_m68 and RNA. Our study illustrated the molecular basis for UGUA recognition by the CFIm complex, suggested a possible mechanism for CFIm mediated alternative polyadenylation, and revealed potential links between CFI_m and other mRNA processing factors, such as the 20 kDa subunit of the cap binding protein (CBP20), and the splicing regulator U2AF65.