Objective To investigate the application of ultrasound and 64-slice spiral CT in the diagnosis of acute appendicitis. Methods Sixty-five patients with pathologically or clinally confirmed acute appendicitis were underwent ultrasound and CT examina-tion before operation or conservative treatment.Compared with pathology,the accuracy of CT and B-ultrasound imaging were ana-lyzed.Results Fifty-eight cases were correctly diagnosed by CT and 48 cases were correctly diagnosed by ultrasound,the accuracy was 89.23% (58/65)and 73.85% (48/65),respectively.There was a statistically significant difference between two groups (χ2 =5.1 1,P =0.024).Conclusion The accuracy of multi-slice spiral CT is higher than ultrasound in the diagnosis of acute appendicitis.