In March 2019, the European Commission mandated EFSA to revise itsguidance document on the risk assessment of plant protection products on bees (Apis mellifera, Bombus spp. and solitary bees). One of the aspectsof this revision involvesareview of the evidence on bee background mortality, which is addressed in this report. Eight different assessment questions were formulated in order to account for the variousbee groups, the difference between active and inactive periods, and to specifically consider the influence of beekeeping practices on honey bees. A systematic literature review and a survey ofbeekeepers from several EU countries were used as the main sources of information.The available dataset for honey bees is large enough to draw rather robust conclusions. The results of the analysis highlight important differences in levels of background mortality between the castes and roles of the bees in the colony. The impact of beekeeping practices on mortalityappears to be very limited, but not completely absent. The dataset for bumble bees and solitary bees is smaller and too scattered to be able to draw robust conclusions. Nevertheless,it issufficient to be able to define a plausible range of background daily mortality rates, and to provide some indications of differences among species.