AbstractMotile flagella are crucial for human fertility and embryonic development. The distal tip of the flagellum is where growth and intra-flagellar transport are coordinated. In most, but not all, model organisms the distal tip includes a “singlet region”, where axonemal doublet microtubules terminate and only complete A-tubules extend as singlet microtubules to the tip. How a human flagellar tip is structured is unknown. Here, the flagellar tip structure of human spermatozoa was investigated by cryo-electron tomography, revealing the formation of two complete singlet microtubules from both the A-tubule and B-tubule of doublet microtubules. This different tip arrangement in human spermatozoa shows the need to investigate human flagella directly in order to understand their role in our health and disease.