Objectives: Lung adenocarcinomas with or without epidermal growth factor receptor (EGFR) mutations have shown different drug effects against EGFR inhibitors. But it is not very clear if EGFR mutation status affects the biological behavior of lung adenocarcinoma, because tumor gene regulation is very complicated and can be affected by many factors. We aimed to explore if EGFR mutation status is related with tumor malignant degree by investigating the relevance of EGFR mutation status with DNA content and aneuploid peaks of lung adenocarcinoma cells in pleural fluids without using EGFR-TKIs. Materials and Methods: 591 cases of lung adenocarcinoma patients in Hebei Tumor Hospital who had undergone EGFR gene detection and DNA quantitative analysis were collected from January 2012 to August 2018.They were divided into two groups: EGFR mutant group and non-mutant group. EGFR mutations were detected by Amplification Refractory Mutation System (ARMS) and ABI 7500 Fluorescence quantitative PCR with pleural effusions. DNA content and aneuploid peaks were detected by LD DNA image cytometry (DNA-ICM). Rank-sum test of SPSS 16 was used for statistical analysis. Results: The maximum DI, the mean DI of the first 20 cells greater than 5C, the percentage of cells greater than 5C and the number of cells greater than 9C of the first 20 cells in the mutant group were all higher than those in the non-mutant group, having statistical significance (p<0.001); the peaks of aneuploid cells in the mutant group occurred more often than those in the non-mutant group, having statistical significance (p<0.001). Conclusions: Our study has shown that advanced lung adenocarcinomas with EGFR-mutations had higher DI values, more aneuploid cells and more frequent aneuploid peaks compared with those without EGFR-mutations, suggesting that advanced lung adenocarcinomas with EGFR mutations are more aggressive than those without EGFR mutations.