Sperm tail development is a complex process that requires the selective transport of thousands of proteins through the ciliary gate/transition zone and then to precise locations within the ciliary compartment (tail). We have recently identified a damaging point mutation in the centriole gene CEP76 in an infertile man. Cep76 is highly testis expressed and is enriched within spermatids. To test the role of CEP76 in sperm transition zone function and male fertility we generated a knockout mouse model. Cep76 knockout males were sterile due to the absence of progressive sperm motility. In addition, sperm were on average 15% shorter than sperm from wild type littermates (p < 0.0001). Further, sperm head morphology was abnormal in 40% of knockout cells (p < 0.0001) and decapitation was three-fold more frequent (p < 0.001). We used electron microscopy to further explore these structural defects, which revealed several significant tail abnormalities – the absence of inner dynein arms in the tail axoneme, the absence of a clear annulus structure, abnormal mitochondrial morphology, and duplicated neck structures in knockout sperm. A proteomic analysis of wild type and Cep76 knockout sperm revealed 32 differentially regulated proteins, including several mitochondrial proteins and DNAH2 – a key component of inner dynein arms. Localisation of DNAH2 via immunofluorescence revealed it to be ectopically localised at the sperm neck in knockout cells, consistent with impaired DNAH2 loading into the sperm tail. Collectively, our data identify CEP76 as a key gatekeeper of protein entry into the developing sperm tail.