Background/aim: Understanding the causes of under-five deaths is key to realizing sustainable developmental goals. The aim of this descriptive study was to investigate the causes of under-five mortality in İstanbul during 2011 and compare the findings to those of 1988 and 2000. Materials and methods: All burial records of İstanbul were evaluated, and cemetery records of 1494 children, who died at under five years of age and were buried in İstanbul Metropolitan Municipality Cemeteries between 1 January and 31 December 2011, were analyzed. Several sociodemographic characteristics and causes of death were compared with the results of studies carried out in 1988 and 2000 in İstanbul with similar methods. Results: Under-five mortality rate was lower in 2011 than in 1988 and 2000. Of all deaths, 58.8% had occurred in the neonatal period and most were in the first day of life, similarly to those of 1988 and 2000. The proportion of deaths in the age group of 1-4 years was found to be increasing. Prematurity and perinatal causes remained the main cause of death under five years of age in İstanbul during the 23-year period. Unknown causes, due to misclassification, were still seen in a relatively high proportion. Conclusion: Under-five mortality rate and death due to infectious diseases decreased in İstanbul from 1988 to 2011. Our findings showed a need for more emphasis on perinatal events and better evaluation of causes of death in clinical practice.