The Cry proteins produced by Bacillus thuringiensis Berliner are effective bioinsecticides against different insect pests. The primary threat to their long-term use is evolution of resistance by pests. Cry toxins are produced as protoxins activated in larval-gut lumen. The toxins bind to receptors that induce oligomerization and insertion into the membrane forming ionic pores that kill the cells and the larvae. The Cry1AMod toxins were created by genetic engineering of Cry1A by the deletion of the N-terminal end. These proteins kill resistant insects, in particular, those that have eliminated or modified one of the toxin receptors. Cry1AMod toxins could have potential to be used to control insect resistance. However, for the future use of these proteins in the field, it is important to demonstrate their mechanism of action is similar to the wild-type Cry1A toxins. Here we summarize results regarding the mode of action of CryMod toxins showing they have a similar mechanism as wild-type Cry toxins.