Organising pneumonia is a histopathological entity characterised by intra-alveolar buds of granulation tissue, intermixed myofibroblasts and connective tissue. Cryptogenic organising pneumonia (COP) is characterised by this particular histopathological pattern, along with typical clinical and imaging features, when no other underlying aetiology is found. COP (previously known as bronchiolitis obliterans organising pneumonia [BOOP]) is one of the rare variants of interstitial pneumonias. This condition is characterised by a rapid clinical and radiological improvement with steroid treatment. Here we are reporting a case of COP in adult female with discussion on approach and basic pathophysiology of this type of pneumonia.