Bacteriophage λ that binds to liposomes bears its receptor maltoporin (LamB) and is able to inject its DNA into the internal space. During this process, the liposomes are permeabilized, suggesting that a transmembrane channel has formed (Roessner and Ihler (1986) J. Biol. Chem. 261, 386–390). This pore possibly constitutes the pathway used by λ DNA to cross the membrane. We reconstituted purified LamB from Shigella in liposomes that were incubated with λ phages. Addition of this mixture to a bilayer chamber resulted in the incorporation in planar bilayers of high-conductance channels whose conductance, kinetics and voltage dependence were totally different from those of maltoporin channels.