The formation of band-like heterogeneities in deformed grains and the evolution of their microtexture components during large plastic deformations is examined in Al bicrystals. The study has focussed on bands developed by plane strain compression in {100}< 001 >/{110}< 011 > (soft/hard)-oriented high purity aluminium bicrystals with the boundary plane situated parallel to the compression plane. The character of the bands.was determined by systematic local orientation measurements using EBSD in SEM-FEG scanning electron microscope and also by transmission electron microscopy (TEM/CBED) at specific locations. The bicrystal deformation analysis shows that the microtexture evolution in each crystallite is quite different. Very strong deformation banding in the 'cube' grain is initiated by strain incompatibilities and giving initial rotations about transveres direction. At very high strains where the flow is inhomogeneous, clearly defined rotations about a < 112 > axis are observed, suggesting localized single {110} < 110 > slip in areas of the band. The 'hard' {110}< 011 >-oriented grains are more stable under plane strain conditions except for the zone near the grain boundary where strong micro-textural/structural disturbances are observed.