Objective To elevate the clinical diagnosis of BAC (bronchioloalveolar carcinoma) so as to reduce misdiagnosis by using retrospective analyses. Methods Retrospective analyses were used to study the five BAC patients, who were diagnosed in our hospital from 2013 to 2014. Results 4 of 5 male, and 1 female, age between 50 and 73, were diagnosed as pneumonia. All of them were made a definite diagnosis as BAC after performing transbronchial lung biopsy. Conclusion BAC is an exceptional lung adenocarcinoma and there is no specific clinic symptom. BAC was easily misdiagnosed as common lung pneumonia. There will be serious consequences after misdiagnosis of BAC due to its poor prognosis. Those patients who were misdiagnosed as common lung disease, but there was no obvious improvement after accepting long anti-infective therapy and there was negatively detection of pathogenic bacteria in them, are needed to perform all other clinical examination to clarify a diagnosis, and to further improve the prognosis of the patients.