Objective To study the changes of serum myeloperoxidase (MPO) and amylin levels in elderly obstructive sleep apnea hypopnea syndrome (OSAHS) patients with different severities and its significances. Methods A total of 134 elderly OSAHS patients admitted to our hospital from February 2012 to October 2016 were retrospectively recruited in this study. According to their apnea hypopnea index (AHI), they were divided into severe group (n=55), moderate group (n=41) and mild group (n=38). Polysomno-graphy (PSG) indicators, MPO and amylin levels were compared among the 3 groups. Spearman correlation analysis was used to analyze the influencing factors of amylin and MPO levels. SPSS statistics 13.0 was employed to analyze the data. Analysis of variance or Chi-square test was applied to make intergroup comparison according to different data types. Results Compared with the severe group, AHI, oxygen desaturation index (ODI), apnea and hypopnea frequency were decreased significantly, and the lowest oxygen saturation (LSaO₂) and mean arterial oxygen saturation (MSaO₂) at night were increased obviously in the mild group and the moderate group (P<0.05). Before continuous positive airway pressure (CPAP) ventilation treatment, the severe group had notably higher serum levels of amylin [(47.85±6.41) vs (20.29±3.06) and (31.57±5.27)ng/ml] and MPO [(37.92±9.88) vs (7.61±2.04) and (23.33±4.56)ng/mg] than the mild and moderate groups (P<0.05). In 6 months and 1 year after the treatment, the serum levels of amylin [(34.17±4.96) and (27.14±3.86) vs (47.85±6.41)ng/ml] and MPO [(21.06±8.39) and (12.17±7.53) vs(37.92±9.88)ng/mg] were significantly lower in the patients of the severe group when compared with the levels before treatment (P<0.05). Spearman correlation analysis showed that MPO and amylin levels were negatively correlated with LSaO₂ and MSaO₂, and positively correlated with AHI and apnea frequency. Conclusion Serum amylin and MPO levels show reference values in evaluation of the risk for insulin resistance and of the therapeutic effect of CPAP in elderly OSAHS patients.