This chapter describes an ethnographic study of the use of information technology (IT) in a laboratory engaged in research related to the Human Genome Project. The use of IT is portrayed as strategic, facultative and motivated. The role played by IT in narratives about work in the laboratory, about training needs and about discoveries is also strategic. It is suggested that this attitude towards IT, and the resulting invisibility of IT developers in the laboratory, contributes to the viewing of IT within the laboratory as just another scientific instrument, providing a transparent window on nature. This analysis draws on research in sociology and history of science about the role of instruments in scientific expertise, in discoveries, experiments, scientific organisation and research directions.