IntroductionThe aim of this study was to compare the efficacy and safety of 3 years of HDM subcutaneous immunotherapy (HDM-SCIT) in allergic asthma (AA) children with mono- and polysensitized. MethodsThis was a retrospective observational study, 51 AA children (aged 4–14 years) who had completed 3 years of standardized HDM-SCIT were enrolled in. Based on skin prick tests (SPT) and allergen-specific IgE antibody (sIgE) test results, children were classified into two groups: the monosensitized group (n = 31) and the polysensitized group (n = 20). Total asthma symptoms score (TASS), total medication score (TMS), visual analog scale (VAS) scores, fractional exhaled nitric oxide (FeNO), lung function parameters, and adverse reactions were evaluated before treatment and at 6 months, 1, 2, 3 years of HDM-SCIT. ResultsIn terms of effectiveness, compared to baseline, TASS, TMS, VAS, FeNO and lung function parameters were significantly improved in both groups after 3 years of HDM-SCIT (all P < 0.05). The comparison between the two groups showed that efficacy indicators were no statistically significant difference at follow-up time points (all P > 0.05) except PEF%pred at 6 months (P = 0.048). In terms of security, the number of adverse reactions in both groups also no statistical difference between the two groups (all P > 0.05). ConclusionThis study confirmed that no significant difference was observed in the clinical efficacy and safety of HDM-SCIT between mono-and polysensitized children with allergic asthma.