It is widely recognised that *b is a rare phoneme in the Proto-Indo-European stop system, but there is no agreement as to the reality of the few alleged examples of Proto-Indo-European *b. This paper approaches the problem from a phylogenetic perspective, assuming that Anatolian and Tocharian were the first two subgroups to separate from the rest of the Indo-European language family. From this perspective there is no evidence at all for the existence of Proto-Indo-European *b in initial position. In medial position there are a few possible examples, although none of them can be regarded as certain.