Peroxisomal protein import is essentially different to the translocation of proteins into other organelles. The molecular mechanisms by which completely folded or even oligomerized proteins cross the peroxisomal membrane remain to be disclosed. The identification of a water-filled pore that is mainly constituted by Pex5 and Pex14 led to the assumption that proteins are translocated through a large, probably transient, protein-conducting channel. Here, we will review the work that led to the identification of this translocation pore. In addition, we will discuss the main biophysical features of the pore and compare it with other protein–translocation channels.