A case of synchronous adenocarcinoma of lung and extranodal marginal zone/low-grade B-cell lymphoma of mucosa-associated lymphoid tissue (MALT) is reported. Primary pulmonary non-Hodgkin's lymphoma is relatively rare, however, the majority of these lesions are low-grade B-cell lymphomas of MALT. After the stomach, the lung is the second most common location for such latter lesions. Lung adenocarcinoma in selected countries is fast becoming the leading form of non small-cell lung carcinoma. To our knowledge, this synchronous occurrence in the lung has not been previously reported. Such associations have been primarily limited to gastric lesions where an association with Helicobacter pylori infection has been identified. This case report highlights the importance of adjunctive diagnostic investigations such as molecular techniques in conclusive analysis of synchronous cases such as ours.