BACKGROUND: Intussusception of the large bowel in adults is a very rare pathological condition. However, it has its clinical importance because intussusception is very often associated with an intraluminal lesion. CASE REPORT: We report two cases of the large bowel intussusception, ileocolic and colorectal. Both intussusceptions were associated with a malignant tumor. However, the clinical presentation was different. One of the intussusceptions was of non-transient character, while the second one resolved spontaneously before operation. Both patients underwent surgery and malignant tumors were found and removed. RESULTS: The purpose of the article is to draw attention to intussusception and emphasize that intussusception, either transient or non-transient, should be further examined. CONCLUSIONS: The intussusception may be the first and the only signal of the existence of a malignant tumor, very often colorectal carcinoma. and R. Vobořil, J. Fanta, P. Bačkovský, D. Ehrenberger, J. Vobořilová