Objective To investigate the prognostic value of the ratio of lactic acid to albumin (Lac/Alb) in elderly patients with sepsis complicated with multiple organ dysfunction syndrome (MODS). Methods A retrospective study was performed on 162 elderly patients with sepsis complicated with MODS who admitted in the First Aid Center and ICU of our hospital from January 2015 to June 2017. They were divided into survival group (n=56) and death group (n=106) according to their 14-day survival. The changes of Lac, Alb and Lac/Alb ratio in 0,4 and 48 h after treatment were studied, and the scores of Acute Physiology and Chronic Health Evaluation Ⅱ (APACHE Ⅱ) and Sequential Organ Failure Assessment (SOFA) at admission were recorded in the 2 groups. SPSS statistics 19.0 was used for data processing. Receiver operating characteristic (ROC) curve was used to analyze the prognostic value of Lac, Alb and Lac/Alb ratio in MODS patients. Pearson correlation analysis was also used. Results At 0,4 and 48 h after treatment, the death group had significantly higher Lac [(7.84±2.65) vs (4.58±1.52)mmol/L, (9.23±4.16) vs (3.60±1.18)mmol/L, (10.58±4.72) vs (2.14±0.85) mmol/L] and Lac/Alb ratio [(0.38±0.17) vs (0.19±0.12), (0.51±0.20) vs (0.14±0.08), (0.67±0.23) vs (0.08±0.03)], but obviously lower Alb [(22.26±4.35) vs (25.38±4.72)g/L, (19.15±4.07) vs (27.14±5.20)g/L, (16.30±3.52) vs (31.73±6.82)g/L], when compared with the survival group (P<0.05). The results of ROC curve showed that when the best cut-off value of Lac/Alb ratio at 48 h was 0.45, the ratio well predicted the prognosis of MODS with a sensitivity of 93.6% and a specificity of 86.5%. Lac/Alb ratio at 48 h was positively correlated to APACHE Ⅱ (r=0.725, P<0.01) and SOFA scores (r=0.806, P<0.01). Conclusion Lac/Alb ratio is closely related to the severity and prognosis of patients with MODS, and the ratio at 48 h is of higher value in predicting the prognosis.