ObjectiveTo investigate the changes and clinical significance of levels of serum Sal-like protein 4(SALL4) and FMS-like tyrosine kinase 3 ligand (Flt3L) in adult patients with acute lymphoblastic leukemia (ALL).Methods86 adult ALL patients who visited our hospital from October 2021 to October 2023 were selected as the research group. Meantime, 86 healthy volunteers in our hospital were selected as the control group. According to the prognosis of ALL patients, 21 patients were divided into poor prognosis group and 65 patients with good prognosis group. ELISA was applied to measure the expression levels of serum SALL4 and Flt3L. Logistic regression analysis of prognostic factors of ALL patients was done. ROC curves were plotted to analyze the predictive value of serum SALL4 and Flt3L levels for the prognosis of ALL.ResultsCompared with the control group, the serum SALL4 level in the research group was higher (P<0.05), and the Flt3L level was lower (P<0.05). Compared with the good prognosis group, the poor prognosis group had higher serum SALL4 level (P<0.05) and lower Flt3L level (P<0.05). Logistic regression analysis results showed that serum SALL4 and Flt3L were the prognostic factors of ALL patients (P<0.05). The combination of serum SALL4 and Flt3L had the highest AUC (0.971) in predicting the prognosis of ALL patients, which was better than individual prediction (Z_{combination-SALL4}=2.839, P=0.005; Z_{combination-Flt3L}=2.201, P=0.028), with a sensitivity of 95.24% and a specificity of 89.23%.ConclusionSerum SALL4 level is elevated and Flt3L level is reduced in ALL patients. The combination of the two is more effective in predicting the prognosis of ALL patients.