Cambridge Antibody Technology Group Plc, (CAT) was a biotechnology company with a core focus on antibody therapeutics, primarily using phage display and ribosome display technology.

Founded in 1989, CAT was acquired by AstraZeneca for £702m in 2006. AstraZeneca subsequently acquired MedImmune LLC, which it combined with CAT to form a global biologics division called MedImmune.

CAT was headquartered in Cambridge, UK.