Clinical need and developments in pathology and molecular biology require our cancer classifications to be constantly updated to keep them relevant and useful. A review of lung cancer classification is due and has been initiated with new proposals on classification of lung adenocarcinoma. Other major lung cancer types also deserve a similar consideration. As well as addressing the categories of tumor, as signed out in surgical resection specimens, recent proposals on small diagnostic-sample reporting would be an important addition to any new classification. The huge increase in data on the molecular biology of lung cancer has improved our understanding of these diseases, has driven improved therapy for some patients, and must be reflected in the way lung cancer is classified.