Fibroblast growth factor receptor-1 (FGFR-1) has been implicated in the process of cardiogenesis, although the underlying molecular mechanisms are poorly understood. In this study, we report the regulation of FGFR-1 expression by related transcriptional enhancer factor-1 (RTEF-1) in vitro (endothelial cells) and in vivo (RTEF-1 transgenic mice). FGFR-1 promoter activity, FGFR-1 mRNA and protein level were measured in bovine aortic endothelial cells (BAEC) in response to RTEF-1 and in endothelial cells isolated from livers in RTEF-1 transgenic mice. RTEF-1 stimulated FGFR-1 promoter activity in a dose-dependent manner. RTEF-1 enhanced FGFR-1 mRNA (4-fold) and protein expression (3.5-fold) whereas RTEF-1 siRNA decreased FGFR-1 protein expression (4-fold). FGFR-1 mRNA and protein expression were also increased in endothelial cells isolated from livers of RTEF-1 transgenic mice. Furthermore, RTEF-1 enhanced tubule formation whereas this was decreased by RTEF-1 knockdown. Moreover, increased relaxation of microvessels was found in RTEF-1 transgenic mice compared to wild-type mice. Our results indicate that RTEF-1 acts as a transcriptional stimulator of FGFR-1 in endothelial cells through its activation of the FGFR-1 promoter. RTEF-1 thus plays an important role in the regulation of FGFR-1 expression. These findings help further understand FGFR activity in angiogenesis and may lead to new therapeutic targets in ischemic vascular disorders.