Mucocele of the appendix due to mucinous cystadenoma is a rare clinical finding. Approximately half of the patients are asymptomatic. It's defined as the dilatation of the appendiceal lumen due to abnormal accumulation of mucus in to it. The pseudomyxoma peritonei, as a result of rupture of the appendix, is the most dangerous complication. We present two case reports of patients that were presented in our Department with different clinical findings. The first patient was presented with symptoms of acute appendicitis, while the second patient showed with atypical symptoms such as abdominal pain, a palpable mass in the right iliac fossa and a diagnosed mucocele of the appendix with the use of computerized tomography. In both patients was performed an appendicectomy and the final histopathology diagnosis confirmed the presence of the mucinous cystadenoma of the appendix which caused the creation of the mucocele. In conclusion mucocele is a rare tumor which must be considered in the differential diagnosis of a mass in the right lower quadrant of the abdomen.