Provided are a wide concentration range, especially high concentration, substantially salt-free anti-prolactin receptor antibody formulations that are substantially isosmotic and of low viscosity. In particular, a preferred embodiment includes: an anti-PRLR antibody formulation, comprising: a. 10 mM histidine, b. 75 ppm or 80 ppm polysorbate 80, c. 205 mM to 292 mM sucrose or trehalose, d. 10 mM to 50 mM arginine, e. 5 mM or 10 mM methionine, and f. 1 mg/ml to 60 mg/ml of an anti-PRLR antibody, wherein said anti-PRLR antibody formulation has a pH ranging from pH 5.0 to pH 6.5, wherein said anti-PRLR antibody formulation contains no inorganic salt and wherein said anti-PRLR antibody is a human IgG2 monoclonal antibody which comprises a heavy chain and a light chain, wherein the amino acid sequence of said heavy chain is according to SEQ ID NO: 7, and the amino acid sequence of said light chain is according to SEQ ID NO: 1.
