The pathology of the vermiform appendix remains one of the topical issues of abdominal surgery. Some of its diseases are rare, but may present difficulties for diagnosis and treatment and are fraught with serious complications. These include invagination (intussusception) in isolated form or with other structures of the ileo-cecal region. Invagination may be caused by other previously unidentified lesions (benign or malignant tumors, mucocele, endometriosis, parasites). On the other hand, the invaginated appendix simulate tumor and tumor-like forms of the cecum and lead to diagnostic errors. The article describes a rare case of a complex variant of appendicular invagination with acute appendicitis. According to the morphological data, the possible mechanism of invagination was as follows: invagination of the appendix from its tip into itself with the fragments of mesappendix, later followed by complete invagination into the cecum – type V due to the progression of type I, according to classification of McSwain. The wall of the invaginated appendix had an inverted structure with an external disposition of the mucosa. The literature data relating to the history of the study of the problem, classifications, causes and mechanisms of appendicular invagination are reviewed.