Hello, Here are the answers for multi-level (>3) hierarchical anova. there is a R packages designed for this kind of problem : HIERFSTAT (http://www2.unil.ch/popgen/softwares/hierfstat.htm) by Jérôme Goudet. I also had an answer mentionning that the Statistica software seemed to be able to handle it with no problem. Thanks for all the answers ! beltrame@mnhn.fr