The disaccharide trehalose is found to be effective for stabilization of active recombinant retroviruses in an amorphous dry state achieved through ambient‐temperature vacuum dehydration of retroviral supernatants. Studies revealed that trehalose is a significantly better desiccation protectant than sucrose, glucose, and dextran: dextran has essentially no protective effect on retroviral survival after drying and rehydration. X‐ray diffractometry of the retroviral supernatant dried with trehalose demonstrated its amorphous nature. The ability to dehydrate retroviral stocks at ambient temperatures into a stable glassy state will have a profound effect for researchers and commercial biotechnology companies which supply retroviral vectors for human gene therapy and basic research.