Predatory pricing to gain market share has long been held to be anticompetitive. Predatory pricing is the exercise of market power on the sale or output side, whereas predatory bidding affects the buying in the market or the input side. This paper considers whether the test of predatory pricing should be applied to predatory bidding claims. The theoretical and practical similarities of predatory pricing and bidding are discussed along with a comparison of monopsony and monopoly powers in the market place.