Aims Toexaminetheliteratureontheassociationsbetweenalcoholusedisorders(AUD)andmajordepression(MD), and to evaluate the evidence for the existence of a causal relationship between the disorders. Methods PsycInfo; PubMed; Embase; Scopus; ISI Web of Science database searches for studies pertaining to AUD and MD from the 1980 to the present. Random-effects models were used to derive estimates of the pooled adjusted odds ratios (AOR) for the links between AUD and MD among studies reporting an AOR. Results The analysis revealed that the presence of eitherdisorderdoubledtherisksof theseconddisorder,withpooledAORsrangingfrom2.00to2.09.Epidemiological data suggest that the linkages between the disorders cannot be accounted for fully by common factors that influence both AUD and MD, and that the disorders appear to be linked in a causal manner. Further evidence suggests that the mostplausiblecausalassociationbetweenAUDandMDisoneinwhichAUDincreasestheriskof MD,ratherthanvice versa. Potential mechanisms underlying these causal linkages include neurophysiological and metabolic changes resultingfromexposuretoalcohol.Theneedforfurtherresearchexaminingmechanismsof linkage,genderdifferences in associations between AUD and MD and classification issues was identified. Conclusions The current state of the literaturesuggestsacausallinkagebetweenalcoholusedisordersandmajordepression,suchthatincreasinginvolvement with alcohol increases risk of depression. Further research is needed in order to clarify the nature of this causal link, in order to develop effective intervention and treatment approaches.