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Aim To estimate the proportional contribution of influenza viruses (IV), parainfluenza viruses (PIV), adenoviruses (AV), and coronaviruses (CV) to the burden of severe acute low-er respiratory infections (ALRI). Methods The review of the literature followed PRISMA guidelines. We included studies of hospitalized children aged 0-4 years with confirmed ALRI published between 1995 and 2011. A total of 51 studies were included in the final review, comprising 56 091 hospitalized ALRI episodes. Results IV was detected in 3.0 % (2.2%-4.0%) of all hospi-talized ALRI cases, PIV in 2.7 % (1.9%-3.7%), and AV in 5.8% (3.4%-9.1%). CV are technically difficult to culture, and they were detected in 4.8 % of all hospitalized ALRI patients in one study. When respiratory syncytial virus (RSV) and less common viruses were included, at least one virus was de-tected in 50.4 % (40.0%-60.7%) of all hospitalized severe ALRI episodes. Moreover, 21.9 % (17.7%-26.4%) of these vi-ral ALRI were mixed, including more than one viral patho-gen. Among all severe ALRI with confirmed viral etiology, IV accounted for 7.0 % (5.5%-8.7%), PIV for 5.8 % (4.1%-7.7%), and AV for 8.8 % (5.3%-13.0%). CV was found in 10.6 % of virus-positive pneumonia patients in one study. Conclusions This article provides the most comprehen-sive analysis of the contribution of four viral causes to severe ALRI to date. Our results can be used in further cost-effectiveness analyses of vaccine development and implementation for a number of respiratory viruses