The Taplejung tectonic window in eastern Nepal has a complex geological history of polyphase deformation. The window is made up of the Lesser Himalayan Sequence comprising low-grade metamorphic rocks and is surrounded by the kyanite-sillimanite bearing Greater Himalayan Crystallines. Both sequences are of Proterozoic age and separated from each other by the Main Central Thrust. Strain analysis on samples from the Greater Himalayan Crystallines revealed flattened and constricted strain ellipsoids indicating two main deformation phases. The geologically representative strain values range from 0.087 to 0.525. The strain values are very high, typical for zones near the thrust where ductile deformation prevails. Microstructural analysis indicates an overprint of a high-temperature fabric, whereas the orientations of rotated boudins and fabric elements show a top-to-the south sense of shear.