The authors analyse the ultrasonographic findings of 10 cases of appendiceal mucocele retrospectively. In a total of 10 cases, 6 cases showed only cystic masses with posterior reinforcement . The remaining 4 cases showed internal echoes in the cysteic massses. Differential diagnosis of mucocele from periappendiceal abscess in not possible in ultrasound. The possibility of mucocele should be considered if cystic mass in right lower quadrant abdomen is observed in ultrasound.