Ritonavir, a protease inhibitor sold under the brand name Norvir®, is an antiviral medication that effectively targets the human immunodeficiency virus (HIV). Being probably the most important and best-known example of the crystal polymorphism in the field of pharmaceutics, ritonavir has been extensively studied in the last 30 years, which eventually led to the discovery of its new polymorph, Form III, in 2023. So far, two crystal structures of both Forms I and II of ritonavir were deposited in CCDC database. The aim of this study was to revisit those crystal structures, using NMR crystallography by recording the