The aim of this study was to evaluate the relationships between physicochemical properties and aerosolisation performance of different grades of lactose. Sieved lactose grades showed similar particle size distributions and good flow properties but different particle shape, particle surface texture, and particle solid state. Lactose particles with rougher surface produced improved salbutamol sulphate (SS) homogeneity within DPI formulation powders. Lactose particles with more elongated shape and the rougher surface showed smaller adhesion force between lactose and salbutamol sulphate. Lactose powders with higher bulk density and higher tap density produced smaller emission and higher drug loss of SS. Linear relationships were established showing that in order to maximize SS delivery to lower airway regions, lactose particles with more elongated shape, more irregular shape, and rougher surface are preferred.