Twenty years ago, V. P. Skulachev put forward the revolutionary concept of the chemiosmotic sodium cycle which is an integral of the paradigm of modern bioenergetics. This fundamental concept stimulated studies in many areas and yielded plenty of sometimes quite unexpected (and thus most valuable) discoveries. In particular, variations of the sodium cycle have been found in a surprisingly large number of pathogenic microorganisms, raising the question about the possible link of sodium energetics and virulence. This brief review discusses some paradoxes related to the Na(+) cycle in an important human pathogen, Vibrio cholerae.