Background and aim: A cure for the heterogeneous hematological malignancy Multiple Myeloma (MM) is yet to be developed. To date, the early risk factors associated with poor outcomes in MM have not been fully elucidated. Studies have shown an aberrant complement system in MM patients, but the precise association necessitates elucidation. Therefore, this study scrutinizes the correlation between serum complement level and the disease outcome of MM patients.Materials and methods: A retrospective analysis of 72 MM patients (new diagnosis) with complement C4 and C3 along with common laboratory indicators was done. The Pearson’s χ2 test and the Mann–Whitney U test were done to evaluate categorical or binary variables and inter-group variance, respectively. Kaplan-Meier test and Cox’s proportional hazards regression were employed for quantitation of overall survival (OS) and univariate or multivariate analyses, respectively.Results: The Cox proportional hazard model analysis unveiled the following: platelet≤115.5×10^9/L(HR=5.82，95%CI=2.522-13.436, P<0.001)， complement C4≤0.095g/L(HR=3.642, 95%CI=1.486-8.924,P=0.005), age≥67 years(HR=0.191, 95%CI=0.078-0.47, P<0.001)，bone marrow plasma cell percentage≥30.75% (HR=0.171, 95%CI=0.06-0.482, P=0.001) can be employed as independent predictors of OS. Of these, advanced age, low platelet level, and a high proportion of bone marrow plasma cells have been implicated in poor outcomes in MM patients. Interestingly, a low complement 4 level can function as a new indicator of poor prognosis in MM patients.Conclusion: Low levels of C4 are indicative of a poor outcome in newly diagnosed MM patients.