GEMC1 and MCIDAS are Geminin family proteins that transcriptionally activate E2F4/5-target genes during multiciliogenesis, including FoxJ1 and Ccno. Male mice lacking Gemc1, Mcidas or Ccno were found to be infertile, but the origin of this defect has remained unclear. Here we show that all three genes are necessary for the generation of functional multiciliated cells in the efferent ducts that are required for spermatozoa to enter the epididymis. In mice mutant for Gemc1, Mcidas or Ccno, we observed a similar spectrum of phenotypes, including thinning of the seminiferous tubule epithelia, dilation of the rete testes, sperm agglutinations in the efferent ducts and lack of spermatozoa in the epididymis (azoospermia). These data suggest that defective efferent duct development is the dominant cause of male infertility in these mouse models and this likely extends to patients with the ciliopathy Reduced Generation of Multiple Motile Cilia with mutations in MCIDAS and CCNO.