Succinic acid has been identified to be the natural ligand of the orphan G-protein coupled receptor GPR91. Succinate as an intermediate of the citric acid cycle accumulates in the interstitial space after deterioration of blood supply and might act as metabolic feedback signal. GPR91 mRNA has been described to be mainly expressed in kidney. Functional experiments in animal models revealed that the intravenous injection of succinate led to an increase in plasma renin activity and mean arterial blood pressure, suggesting another role of GPR91 signalling in the development of renal hypertension. To get further information about its cellular localisation we characterized the expression pattern of GPR91 in mouse and rat by immunohistochemistry. In murine kidney the pattern was consistent with published in situ hybridisation data. GPR91 antibody staining was observed predominantly in the juxtaglomerular apparatus (JGA) and in the proximal tubule. In rat, however, the renal expression pattern of GPR91 was different with major staining only in proximal tubule S3 segments and without staining of JGA cells. In extrarenal tissues e.g. in the respiratory epithelium (trachea) GPR91 localization was similar in both species, interestingly, with the most intense staining at the luminal side. Taken together our data show the expression pattern of GPR91 in kidney and extrarenal tissues with some distinct species differences. These findings will guide the functional analysis of GPR91 in further investigations.