This paper investigates how geometrical imperfections, which in most cases are present for impacted laminates, affect the postbuckling behaviour of delaminated composites plates under compression. Delaminations are one of the most frequently appearing material damage due to impact. The influence of different shapes of the geometrical imperfections on the response has been studied. The program system DEBUGS, which is developed and specialized to simulate delamination buckling and growth, is used for the analyses. DEBUGS is based on the finite element program ADINA. It is found that the geometrical imperfections influence the buckling behaviour, and thus also possibly the initiation of delamination growth. A more accurate model of delamination buckling of impact damaged laminated composites should thus include a feature where the initial shape of the composite may be varied, e.g. in a model where the material degradation in the impact damaged zone is modelled.