Objective:To study the clinical characteristics，diagnosis，treatment and prognosis of neonatal appendicitis.Methods:From January 2019 to December 2022，19 neonates with appendicitis（appendicitis group）and 38 neonates with sepsis（sepsis group）admitted to the Neonatal Department of Xi'an Children's Hospital Affiliated to Xi'an Jiaotong University were studied.The characteristics of clinical manifestation，imaging，treatment and prognosis of neonates in two groups were analyzed,retrospectively.Results:Among 19 neonates with appendicitis，31.6% were premature，the mean birth weight was（2 927.9±796.2）g，male∶female=2.17∶1.Abdominal distention（8/19，42.1%）and fever（8/19，42.1%）were the first symptoms of appendicitis，and the first symptoms of sepsis were mainly fever（20/38，52.6%）and poor reaction（7/38，18.4%）.In the appendicitis group，the proportions of abdominal distension（89.5% vs. 5.3%），vomiting（36.8% vs. 2.6%），breast resistance（84.2% vs. 39.5%），mental reaction changing（94.7% vs. 71.1%）and abdominal positive signs（84.2% vs. 5.3%）were significantly higher than those in sepsis group（ P<0.05）.C-reactive protein（CRP）was elevated in 16 neonates with appendicitis and 13 neonates with sepsis，and elevated gradually in 14 neonates with appendicitis. Compared with sepsis group，CRP was higher in appendicitis group（ P<0.05）.Fifteen（78.9%）neonates with appendicitis were diagnosed only by ultrasound，mainly manifested as low echo area or liquid dark area in the right abdomen，thickening of the appendix wall or effusion in the cavity，and liquid exudation.Three（15.8%）neonates with appendicitis were diagnosed by ultrasound and CT.Eight（42.1%）neonates with appendicitis were complicated appendiceal perforation.Fifteen neonates with appendicitis were treated by conservative treatment，four cases were treated by operation，and all of them were cured and discharged. Conclusion:Abdominal ultrasonography should be improved as soon as possible in neonates with fever and septicemia，especially those with abdominal symptoms or signs，or CRP increased during treatment，and CT or surgical exploration if necessary,to confirm the diagnosis of neonatal appenditis and early treatment.