The outsourcing of lead optimisation services is a relatively new but growing market. Historically, pharmaceutical companies have been hesitant to outsource activities at the lead optimisation stage of the drug discovery process, but more recently this reticence has largely been put aside. As a result, a growing number of companies with diverse backgrounds and geographical locations are now competing to offer services in this sector. Currently, a particularly significant trend is the move towards 'off-shoring', which promises to drive further changes in this rapidly evolving market in the near future.