In a previous issue of AJHB, Fernandes et al. (2008. Am J Hum Biol 20:185-190.) describe instances of identity by state at multiple short tandem repeat loci between human Y chromosomes belonging to different E-M35 sub-haplogroups. They interpret these findings as evidence for multiple mutational events in at least two loci (M78 and M81). Here, we introduce a novel polymorphic marker (V68), potentially useful to investigate the issue. This marker and sequence data, reported here for the first time, reinforce our previous interpretations on the phylogenetic structure of the E3b haplogroup. We discuss these results in the frame of general approaches to attain robust phylogenetic inferences based on biallelic polymorphism data. © 2008 Wiley-Liss, Inc.