Mitochondrial genome has undergone significant reduction in a course of evolution; however, it still contains a set of protein-encoding genes and requires translational machinery for their expression. Mitochondrial translation is of the prokaryotic type with several remarkable differences. This review is dedicated to one of the most puzzling features of mitochondrial protein synthesis, namely, the system of translational activators, i.e., proteins that specifically regulate translation of individual mitochondrial mRNAs and couple protein biosynthesis with the assembly of mitochondrial respiratory chain complexes. The review does not claim to be a comprehensive analysis of all published data; it is rather focused on the idea of the "core component" of the translational activator system.