Routes to AZT were examd. on a 100-g and a 1-2-kg thymidine scale. In the well-known route, the stages of AZT isolation and purification were considerably simplified to yield, in a two-step process, a 98+% pure white cryst. AZT meeting the 1997 Eur. Pharmacopoeia requirements. The exptl. data were used to design and construct an exptl. production installation (6 kg thymidine) in which implementation tests were run successfully.