The possibility of swelling of single polyelectrolyte chains in dilute aqueous solution by free ions in the presence of a small amount of salt is investigated using a mean-field approach. The swelling of chains by free ions is more likely for larger chains in solutions containing only a small amount of salt. The swollen chains are likely to retain a spherical structure. (C) 2017 The Author. Published by Elsevier Ltd. This is an open access article under the CC BY license