High-pressure polymorphs of WO₃ have been studied with a first-principles pseudopotential method. The medium-range (0.01–20 GPa) and high-range (20–30 GPa) polymorphs have been characterized and are compared with recent experimental results. The main new feature is the appearance of a sevenfold coordinated tungsten in the high-pressure polymorph. The subtle phase transitions that were induced from Raman spectra evolutions have not been confirmed. However, changes in the W–O distances and O–W–O and W–O–W angles may explain the changes in Raman spectra.