Objective:To study the effects of gender on clinical outcomes of extremely low birth weight infants (ELBWI) and to analyze the risk factors of mortality.Methods:From January 2011 to December 2020, ELBWI (birth weight <1 000 g) admitted to the Neonatology Department of our hospital were retrospectively studied. The infants were assigned into the male group and the female group. Incidences of major complications, survival rate and mortality rate were compared between the two groups. The infants were also assigned into survival group and death group according to their clinical outcomes. Binary multivariate unconditional Logistic regression was used to analyze the risk factors of mortality in ELBWI.Results:A total of 637 ELBWI cases were included. 311 cases were in the male group with a survival rate of 57.9% (180/311) and 326 cases were in the female group with a survival rate of 57.4% (187/326). The incidences of neonatal respiratory distress syndrome (RDS), bronchopulmonary dysplasia (BPD), pulmonary hemorrhage and severe intraventricular hemorrhage (IVH) in the male group were significantly higher than the female group ( P<0.05). Significant increases of survival rate existed for both groups year by year ( P<0.01).No significant differences existed in survival rate, mortality rate of infants receiving proactive treatment and mortality rate of infants withdrawing treatment between the two groups ( P>0.05). Multivariate unconditional Logistic regression analysis showed that withdrawing treatment ( P<0.01) and pulmonary hemorrhage ( P<0.05) were associated with increased risks of mortality. Conclusions:Male ELBWI have higher risks of RDS, BPD and severe IVH than female ELBWI. Withdrawing treatment and pulmonary hemorrhage are common risk factors of mortality for both male and female ELBWI.