A new aquaporin was isolated from rat liver based on homology to known aquaporins. A 1408 bp cDNA was sequenced (designated rAQP9L) with a 885 bp open reading frame encoding a 295 amino acid hydrophobic protein, rAQP9L has the greatest amino‐acid sequence identity with human AQP9 (75 %) and a less homology with AQP3 (49 %) and AQP (47 %). Northern blot analysis indicated a 1.4‐kb transcript expressed strongly in liver>testis>brain=lung. Expression of rAQP9L cRNA in Xenopus oocytes increased osmotic water permeability by 6‐folds which was inhibited by 0.3 mM mercury chloride by 42 %. rAQP9L also facilitated glycerol and urea transport by 2‐ and 5‐folds, respectively. The large discrepancy of tissue distribution between hAQP9 and rAQP9L suggest that rAQP9L is a new aquaporin, which is involved in transport of urea as well as water in liver.