Apoptosis is an important process in a wide variety of biological systems, and dysregulation of apoptosis is implicated in many human diseases, including malignancy. In fact, cancer cells demonstrate resistance to a variety of apoptotic stimuli, so that an understanding of the inhibitory mechanisms of apoptosis is particularly important. Recently, researchers have focused on endogenous cellular inhibitors of caspases and found that caspases can be controlled by a variety of inhibitors, such as the inhibitor of apoptosis (IAP) family, and FLICE/caspase 8-inhibitory protein (FLIP), which directly interact with caspases. The IAP family is a widely expressed group of inhibitors, from both physiologic and phylogenic perspectives. The strongest evidence for IAP involvement in cancer is seen with survivin and X-chromosome-linked IAP (XIAP), and the caspase inhibitory effect of XIAP is stronger than that of survivin. Survivin promotes cell proliferation. Inhibition of caspase 8 by FLIP or the phosphatidylinositol 3-kinase/AKT pathway is also an important mechanism for the inhibition of apoptosis. This review summarizes the current and rapidly expanding knowledge concerning the biological functions of caspase inhibitors and the mechanisms for counteracting apoptosis, especially in malignant gastrointestinal cells.