Drug screening, that is, the evaluation of the biological activity of candidate drug molecules, is a key step in the drug discovery and development process. In recent years, high-throughput screening assays have become indispensable for early stage drug discovery because of the developments in synthesis technologies, such as combinatorial chemistry and automated synthesis, and the discovery of an increasing number of new pharmacological targets. Bioluminescence and chemiluminescence represent suitable detection techniques for high-throughput screening because they allow rapid and sensitive detection of the analytes and can be applied to small-volume samples. In this paper we report on recent applications of bioluminescence and chemiluminescence in drug screening, both for in vitro and in vivo assays. Particular attention is devoted to the latest and most innovative bioluminescence and chemiluminescence-based technologies for drug screening, such as assays based on genetically modified cells, bioluminescence resonance energy transfer (BRET)-based assays, and in vivo imaging assays using transgenic animals or bioluminescent markers. The possible relevance of bioluminescence and chemiluminescence techniques in the future developments of high-throughput screening technologies is also discussed.