Morphological and ultrastructural modifications related to the cell injury and leading to cell death have been investigated by using different compounds. Data obtained by treating various cultured cells with a quinone (menadione), a polar solvent (NMF) and a bacterial protein toxin (toxin B fromClostridium difficile) are here reported Differences seem to exist between such injuries, but changes in plasma membrane structure, called surface blebbing phenomenon, represent a common feature which can be in any case detected. Our results also allow to hypothesize an important role of cytoskeleton in such a process.