A study of 701 primary adenocarcinomas of the lung was made at the Department of Pathology of the Hospital da Universidade de Coimbra for a period of fifteen years, between 1990 and 2004. In the same period 382 metastases were diagnosed, mainly from colon (119) and breast (66). The incidence of primary adenocarcinomas varied from 16 cases in 1990 to 49 cases in men and from 12 to 37 cases in women in that period. From 2001 onwards, the incidence was almost coincident in both genders. In the last four years, since 2001, patients were in the seventies at the time of diagnosis and a considerable number of cases were diagnosed after 80 years of age. The criteria defined by the WHO classification of Tumours of the Lung, Pleura, Thymus and Heart 2004 were applied to the primary adenocarcinomas of the lung and as was expected, bronchioloalveolar carcinomas had its incidence in women while acinar adenocarcinomas were diagnosed mainly in men. These conclusions were obtained via surgical specimens and when surgical biopsies were representative and those were mainly in stage IIB and IIIA. A number of 109 cases had the final diagnosis of adenocarcinoma of the lung based on morphology and immunohistochemistry criteria.