Glycolide is an important molecule,as a precursor to the biodegradable and biocompatible polymers poly(glycolic acid) (PGA) and poly(lactic-co-glycolic acid) (PLGA).These polymers are both important in modern-day medicine,with PGA being used in biodegradable sutures and resorbable fixation devices [1] and PLGA being used in drug delivery systems [2].Polymorphism is frequently observed when molecules are subjected to high pressures.Upon deeompression to ambient conditions,the vast majority of polymorph transitions are reversed,with the original form being recovered.The recent case of a monohydrated form of γ-amino butyric acid is a rare example of high-pressure phases being recovered to ambient conditions [3].