The aim of the present study was to investigate the expression and methylation pattern of the angiotensin I converting enzyme 2 (ACE-2) in acute respiratory distress syndrome (ARDS) covid-9 patients. A total of 25 patients with covid-19 ARDS and 20 controls were recruited. Expression of the ACE-2 gene was evaluated by quantitative real time PCR, and methylation of CpG dinucleotides, in the ACE-2 promoter, was quantified using bisulfite pyro-sequencing. Our results showed high expression of the ACE-2 gene in the blood samples of ADRS patients (1.93± 0.67) in comparison to controls (0.62±0.35) (p = 0.03). Correspondingly, in ARDS Bronchoalveolar lavage fluid (BALF) samples, there was a high expression of this gene (1.8±0.78) in comparison to controls (0.58±0.2) (p <0.05). Moreover, the methylation rate of the ACE-2 gene in blood samples of ARDS patients was 64.07 ±6.1 in comparison to controls (80.3 ±7.3) (p<0.0001).  In BALF samples, there was this pattern too (55.07 ±3.1 vs. 72.35±5.1) (p<0.0001). Finally, a significant correlation was found between expression and methylation in BALF (R= -0.54, P= 0.002) and blood (R= -0.321, P= 0.013) samples. These results indicated that aberrant methylation of the ACE-2 promoter might be associated with high expression of this gene and the occurrence of ARDS in covid-19 patients.