GGNBP1 is known as gametogenetin protein 1 (GGN1)-interacting protein. It is specifically expressed in the mitochondria of the testis, while its functional role during spermatogenesis is still unknown. Here, we showed that the disruption of Ggnbp1 resulted in abnormal spermiogenesis in around 40% mice, while the others show no defects in the genital system. Moreover, upon treatment with low dose of bisphenol A (BPA), Ggnbp1 knockout mice were more sensitive to environmental pollutant than control mice. The treatment led to decrease in sperm motility and production of abnormal spermatozoa. These results suggest that GGNBP1 mainly ensures proper spermiogenesis in response to various stresses in male mice. (C) 2020 Elsevier Inc. All rights reserved.