Mitochondria are essential organelles of all eukaryotic cells that play a key role in several physiological processes and are involved in the pathology of many diseases. These organelles form a highly dynamic network, which results from continuous fusion and fission processes. Importance of these processes is underlined by inherited human diseases caused by mutations in two mitochondrial pro-fusion genes: Charcot-Marie-Tooth disease, caused by mutations in Mitofusin 2 gene and ADOA due to mutations in OPA1. During apoptosis, the mitochondrial network is disintegrated and the outer mitochondrial membrane permeabilized, which results in the release of several apoptogenic proteins, including cytochrome c. Although modulating mitochondrial fusion and fission machineries has been reported to influence the apoptotic response to various stimuli, it is still unclear whether fission is absolutely required for apoptosis. In this review, we present the latest progress in the field of mitochondrial dynamics with a particular emphasis on its implication in apoptosis and in diseases.