The present invention relates to new crystalline forms of vilanterol trifenatate, processes for their preparation, and their use in a pharmaceutical composition for the treatment of respiratory diseases, particularly for the treatment of asthma and chronic obstructive pulmonary disease. In particular, the present invention relates to a crystalline form of vilanterol trifenatate characterised in that the form has an XRPD pattern as defined herein having characteristic diffraction angles (2-theta or 2Θ (°)) falling within or at each end of one or more of the following ranges: (a) 3 to 5°, such as 3.8 to 4.4°； and/or (b) 7 to 9.9°, such as 7 to 8.5°； and/or (c) 12 to 13.3°, such as 12 to 13.3°； and/or (d) 16.4 to 17.3°, such as 16.4 to 17.3°； and/or (e)26.8 to 28.3°, such as 26.8 to 28.3°
