Objective To explore the effects of alanyl-glutamine (Ala-Gln) dipeptide supplemented parenteral nutrition (PN) on the short-term outcomes in critically ill adult patients.Methods In this retrospective study,we reviewed the clinical data of critically ill adult patients who were treated by standard PN from January 2006 to December 2011.The length of stay in intensive care unit (ICU-LOS),incidences of infections and multiple organ dysfunction syndrome (MODS),and mortality were compared between the group of Ala-Gln dipeptide supplemented PN (intervention group) and the group of PN without Ala-Gln dipeptide (control group).Results Finially,617 cases were enrolled in the study,including 312 cases in the control group and 305 cases in the intervention group.The ICU-LOS was significantly shorter in the intervention group than that in the control group [(17.2 ± 6.5) d vs.(16.1 ± 5.3) d,P =0.011).Compared with the control group,the incidences of infection (42.9％ vs.33.1％,P =0.011) and MODS (46.5％ vs.38.0％,P =0.030) and the mortality (34.9％vs.25.9％,P =0.014) in the intervention group patients were significantly lower.Conclusion Ala-Gln dipeptide supplemented PN can improve the short-term outcomes of critically ill adult patients.