The present study was designed to investigate whether advanced glycation end products (AGEs) would regulate K(Ca)3.1 channels in cardiac fibroblasts and participate in cell proliferation. Cultured adult rat cardiac fibroblasts were employed to investigate the regulation of K(Ca)3.1 channels by advanced glycation end products-bovine serum albumin (AGE-BSA) and the role of K(Ca)3.1 channels in cell proliferation using approaches of molecular biology. K(Ca)3.1 channel mRNA and protein levels were greatly enhanced in cardiac fibroblasts treated with 200 μg/ml AGE-BSA, and the effects were countered by anti-RAGE antibody or the ERK1/2 inhibitor PD98059, the p38-MAPK inhibitor SB203580, and the PI3K/Akt inhibitor LY294002. In addition, AGE-BSA stimulated cell proliferation and collagen production in cultured cardiac fibroblasts, and the effects were reversed by K(Ca)3.1 blocker TRAM-34, anti-RAGE antibody, or signal inhibitors PD98059, SB203580, and LY294002. These results demonstrate for the first time that AGEs increase the expression of K(Ca)3.1 channels in a RAGE-dependent manner and promote cardiac fibroblast proliferation and collagen production, which is mediated by phosphorylation of ERK1/2, p38-MAPK, and PI3K/Akt signals.