Aquaporin 8 (AQP8) is a water channel protein. Aquaporins are a family of small integral membrane proteins related to the major intrinsic protein (MIP or AQP0). Aquaporin 8 mRNA is found in pancreas and colon but not other tissues.

The human AQP8 protein is 40.4% identical to the plant water channel gamma-TIP, 76.0% identical to mouse Aqp8, 74.9% identical to rat Aqp8, 29.5% identical to human AQP2, and 28.9% identical to human AQP3. Northern blot analysis of human tissues detected a 1.35-kb AQP8 mRNA only in pancreas and colon. Like the genes of non-water-selective aquaporins, the AQP8 gene contains 6 exons; however, its exon-intron boundaries are different from the boundaries of those other aquaporin genes.