In this paper it is shown that in many production networks it is possible to reverse the flow direction in one or more buffers without changing the throughput and buffer content distributions of other buffers in the network. If a network possesses the property that simultaneous reversal of the flow direction in all buffers reverses all the buffer contents, then it is called reversible. If it possesses the property that flow reversal in a single buffer b reverses the buffer content of b and leaves all other buffer contents unchanged, then it is called b-reversible. The reversibility of a production network depends, for the discrete product situation, on the blocking rule used. For networks having a continuous product flow the blocking rule is only important for so-called buffersharing networks. b-reversibility is shown to hold for all buffers b for so-called assembly-disassembly networks. Reversibility is shown to hold for buffersharing networks.