2,3-二磷酸甘油酸（英语：2,3-Bisphosphoglyceric acid，简称为2,3-BPG或2,3-DPG）是糖酵解中间产物1,3-二磷酸甘油酸（1,3-BPG）的一个三碳异构体。2,3-二磷酸甘油酸存在于人的红细胞中，浓度约为5 mmol/L。较之于结合氧气血红蛋白（如当红细胞接近肺部时），这种物质对脱氧气血红蛋白具有更大的结合亲和力（如当红细胞接近呼吸中的组织时），这是由于空间构象改变所致：2,3-二磷酸甘油酸（其尺寸大约9Å）的尺寸正好适合于脱氧气血红蛋白构象（11Å），但是不适合于结合氧气血红蛋白（5Å）。通过降低脱氧气血红蛋白对氧气的亲和力，2,3-二磷酸甘油酸与脱氧气血红蛋白β亚基相互作用，通过构象改变，它推动了剩余结合到血红蛋白上的氧气释放出来，因此增强了红细胞在接近最需要氧气的组织时释放氧气的能力。因而可以说2,3-二磷酸甘油酸是一种别构调节物。

2,3-Bisphosphoglyceric acid (conjugate base 2,3-bisphosphoglycerate) (2,3-BPG), also known as 2,3-diphosphoglyceric acid (conjugate base 2,3-diphosphoglycerate) (2,3-DPG), is a three-carbon isomer of the glycolytic intermediate 1,3-bisphosphoglyceric acid (1,3-BPG). 2,3-BPG is present in human red blood cells (RBC; erythrocyte) at approximately 5 mmol/L. It binds with greater affinity to deoxygenated hemoglobin (e.g. when the red blood cell is near respiring tissue) than it does to oxygenated hemoglobin (e.g., in the lungs) due to spatial changes: 2,3-BPG (with an estimated size of about 9 angstroms) fits in the deoxygenated hemoglobin configuration (11 angstroms), but not as well in the oxygenated (5 angstroms). It interacts with deoxygenated hemoglobin beta subunits by decreasing their affinity for oxygen, so it allosterically promotes the release of the remaining oxygen molecules bound to the hemoglobin, thus enhancing the ability of RBCs to release oxygen near tissues that need it most. 2,3-BPG is thus an allosteric effector.