The development of Aurora kinase inhibitors is a competitive research field, with many inhibitors currently being evaluated in preclinical and clinical studies. Progress during the past few years, both preclinically and clinically, has increased the evidence supporting Aurora kinases as promising molecular targets for the treatment of cancer. Aurora kinase inhibitors differ based on their selectivity within the Aurora kinase family and their cross-reactivities with other kinases. Additional factors that will contribute to the success or failure of the Aurora kinase inhibitors include: routes of administration, drug-like properties, workable combinations with approved drugs, adequate clinical development paths, and the identification of the appropriate patient population. The clinical trial results that are emerging for the most advanced inhibitors are promising, and it is probable that clinical proof of concept will be achieved, and that Aurora kinase inhibitors will be part of treatment for cancer in the future.