Let γ(G) be the domination number of a graph G. The bondage number b(G) of a nonempty graph G is the minimum cardinality among all sets of edges X for which γ(G–X)>γ(G).
In this paper we show that b(G)≤Δ(G) for any block graph G, and we characterize all block graphs with b(G)=Δ(G).