Appendiceal mucocele is an obstructivedilatation of the appendix caused byintraluminal accumulation of mucoid material.It is a rare disease. The incidence is 0.2%to 0.3% of all appendectomied specimens.The brush size to 3 cm are considered to besmall, up to 6 cm - average and more than9 cm - giantCases: the patient 50 years old, man,place of residence: the city of UB songinokhairkhan duureg. Specialists of the driver,in the year immediately 2015,02,02 wasoperated with the diagnosis of acuteappendicitis. Complaints on admission:pain on the right side of the abdomen, anagging pain when moving and walking,stomach rumbling. History of the disease:the pain started with 2015,01,31 at 8 pmfrom the bottom of the abdomen. tookhome chloramphenicol but not helpedso 2015,02,02 year at 9 o’clock enteredvia ambulance. Medical examination: thesatisfactory condition of the active position,the skin clean, moist, blood pressure160/110, pulse 98 beats per minute Spo298%. 10*7,7*5,5 см size /Fig.1-2/ , white /Fig. 3-4/ , smooth surface /Fig.1-4/, insideslimy gray mucinous /Fig. 5-6/ bag /Fig. 5/above listed items on a standard attached,aims to study the histology. The result ofthe following: Mucocele of the appendixwith hyalinized wall and with the additionof acute inflammation with microabscesses.