Ionized haloes around planetary nebulae (PNe) are a quite common phenomenon, being found in about 70% of the elliptical PNe for which adequately deep images exist (cf. Corradi, these proceedings). Physically, one has to distinguish between two different kind of haloes. AGB haloes consist of photo-ionized matter still containing information about the mass loss history during the last thermal pulse cycle on the Asymptotic Giant Branch. A second kind of halo may develop when recombination sets in as a consequence of the fast luminosity drop during the advanced post-AGB evolution. These recombination haloes, which can be confused with real AGB haloes on a pure morphological basis, are not a signature of an AGB mass-loss episode (Corradi et al. 2000).