The aims of this study were to assess the lung lesions and to compare gross observations with histopathological findings in the lungs of slaughter pigs. During August of 2010 through July of 2011, the 1,200 lung samples were randomly collected from slaughtered pigs in Korea. We examined prevalence of lung lesions and classified the lung lesion according to the severity of lung lesions. For the comparison of gross lesions with histopathological findings, BALT hyperplasia was also examined. Among the tested samples, 1,100 (91.7%) had pneumonic lung lesions. In the seasonal prevalence of pneumonic lung lesions, spring was the highest followed by winter, summer and autumn, respectively. The mean pneumonic score ($mean{pm}SD$) was $21.37{pm}17.87$ and the highest gross lesion according to stages was 11~20% (27.2%, 326/1,200). The prevalence of pleuritis was 7.0% and the highest prevalence was determined in summer. In severity, the lungs collected in this study were frequently in chronic stage (36.4%, 437/1,200), and it was shown that BALT hyperplasia was more extensive in chronic lesion. In this study, the prevalence of pneumonic lung lesions showed a high side and appeared particularly high in the spring. Severity of lung lesion was the most prevalent chronic lesions which were consistent with histopathologic findings.