The authors analyse the ultrasonographic findings of 10 cases of appendiceal mucocele retrospectively. In atotal of 10 cases, 6 cases showed only cystic masses with posterior reinforcement. The remaining 4 cases showedinternal echoes in the cystic masses. Differential diagnosis of mucocele from periappendiceal abscess is notpossible in ultrasound. The possibility of mucocele shold be considered if cystic mass in right lower quadrantabdomen is observed in ultrasound.