Recently, Smicklas et al. [I. Smicklas, A. Onjia, S. Raicevic, Dj. Janackovic, M. Mitric, J. Hazard. Mater. 152 (2008) 876-884)] have reported on the effect of pH, contact time, initial metal concentration and presence of common competing cations on hydroxyapatite sorption properties towards Pb2+, Cd2+, Zn2+ and Sr2+ ions. However, application of some experimental procedures and methods, as well as the presentation and interpretation of some data is problematic or erroneous. (C) 2008 Elsevier B.V. All rights reserved.