AIM:To evaluate the long-term attachment of two types of endoclips in the human gastrointestinal tract. METHODS:In this prospective observational study,endoclips were placed and followed-up during endoscopies or using fluoroscopic images as part of a pro s pective feasibility study evaluating external beam radiotherapy (EBRT,wk 1-3) followed by high dose rate brachytherapy (HDRBT with an endoluminal app licator once a week for 3 wk,wk 9-11) in medically inoperablerectal cancer patients. Initially,the type and number of endoclips were chosenrandomly and later refined to 1 Resolution clip (Microvasive) proximal and 2 Quickclips (Olympus) distal to the tumor. Nine consecutive patients from between September 2007 and August 2008 were analyzed. Retention rates were evaluated over three different observational periods [period 1:pre-HDRBT (wk-2-8),period 2:during HD RBT (wk 9-11) and period 3:post-HDRBT (wk 1216)]. RESULTS:In this study,a total of 44 clips were placed during endoscopy,either at the beginning or at the end of period 1. The Resolution clip had a higher overall retention rate than the Quickclip (P = 0.01). After a median period of 81 d after placement (in period 1),longterm retention rates for the Resolution clip and Quickclip clip were 67% and 35% respectively. CONCLUSION:The Resolution clip has a high retention rate and is useful in situations where long-term attachment to the human gastrointestinal mucosa is warranted. AIM: To evaluate the long-term attachment of two types of endoclips in the human gastrointestinal tract. METHODS: In this prospective observational study, endoclips were placed and followed-up during endoscopies or using fluoroscopic images as part of a pro pective feasibility study evaluated external beam radiotherapy (EBRT, wk 1-3) followed by high dose rate brachytherapy (HDRBT with an endoluminal app licator once a week for 3 wk, wk 9-11) in medically inoperablerectal cancer patients. Initially, the type and number of endoclips were chosenrandomly and later refined to 1 Resolution clip (Microvasive) proximal and 2 Quickclips (Olympus) distal to the tumor. Nine consecutive patients from between September 2007 and August 2008 were. Retention rates were evaluated over three different observational periods [ period 1: pre-HDRBT (wk-2-8), period 2: during HD RBT (wk 9-11) and period 3: post-HDRBT were placed during endoscopy, e ither at the beginning or at the end of period 1. The Resolution clip had a higher overall retention rate than the Quickclip (P = 0.01). After a median period of 81 d after placement (in period 1), longterm retention rates for the Resolution clip and Quickclip clip were 67% and 35% respectively. CONCLUSION: The Resolution clip has a high retention rate and is useful in situations where long-term attachment to the human gastrointestinal mucosa is warranted.