Abstract Possible dislocation reactions in face-centred icosahedral quasicrystals are considered from the geometric and energetic points of view. Some typical examples of the reactions between dislocations with different twofold Burgers vectors were confirmed experimentally in a plastically deformed Al-Pd-Mn icosahedral quasicrystal by identification of the Burgers vectors of dislocations in triple-node arrangements. Several examples were investigated in a transmission electron microscope using the defocus convergent-beam electron diffraction technique. On the basis of these dislocation reactions, the experimentally observed fact of an increase in the relative number of dislocations exhibiting a larger phason part of the Burgers vector with increasing plastic strain can be explained.