The pneumonic adenocarcinoma (P-ADC) is defined as primary lung ADC with a radiological pneumonic presentation, usually referred to histologically as ADC with a mixed-invasive and BAC (bronchioloalveolar carcinoma) predominant subtype in the 2004 WHO classification. Invasive mucinous adenocarcinoma (IMA) formerly classified as mucinous BAC usually presents consolidative opacities mimicking pneumonia on CT, on the contrary such pneumonic type adenocarcinoma may occur in nonmucinous adenocarcinoma (NMA) formerly classified as nonmucinous BAC. These tumors should be separated into different categories, because they have clinical, pathologic and genetic differences1)2)3). We compare the CT findings of the pneumonic type adenocarcinoma between IMA and NMA in 20 patients. CT findings of IMA and NMA were compared based on the characteristics of consolidation and accessory opacities. Pleural efuusion and lymphadenopathy were also analyzed. Two CT findings of cavitation or cyst and bulging fissure were statistically significantly different by Fisher’s exact test between them.