BACKGROUND: Following Hamas's 7 October attack, Israel launched extensive aerial bombardments in the Gaza Strip, followed by a large-scale ground invasion. During the first 3 months of the conflict, up to December 31, 2023, the Palestinian Ministry of Health reported that 21,822 Palestinians were killed in Israeli strikes. This study estimates the number of excess deaths in children due to the war in the Gaza Strip in 2023 and assesses how the conflict has impacted the experience of parental loss among children. METHODS: We reconstructed background life tables for the Gaza Strip based on under-five mortality estimates from sample surveys and accounted for casualties due to the 2023 conflict, using the age distribution of deaths from an individual list of 13,101 fatalities reported by the Palestinian Ministry of Health. We employed a kinship matrix model to estimate the number of new orphans in 2023 and the prevalence of maternal and paternal orphanhood. RESULTS: From October 8 to December 31, 2023, our estimates indicate that 8120 children under 18 years of age were killed due to the conflict (with a range of 7099 to 9196 excess deaths). Additionally, 15,127 children (14,716-15,553) lost a father, and 9886 children (9564-10,216) lost a mother due to the conflict. Between 2022 and 2023, the probability of dying in childhood (ages 0-17) increased nearly sixfold for both males and females. The war increased the risk of losing a mother and a father by nine-fold and six-fold, respectively. Compared to the situation in 2022, the proportion of paternal orphans among children aged 0-17 rose by 1.5 times, while the proportion of maternal orphans doubled. CONCLUSIONS: The dramatic number of excess deaths among children and the sharp increases in orphanhood underscores the urgent need to prioritize the well-being and rights of children caught up in the war in Gaza.