Mammalian mitochondrial ribosomes (mitoribosome) have experienced a series of structure recombination during the long period of evolution. Mammalian mitochondrial ribosomes lack several major RNA stem structures of bacterial ribosomes but they are rich in mitochondrial ribosomal proteins (MRPs). All MRPs are synthesized in cytoplasm and imported into the mitochondrial matrix, where they assemble with the two mtDNA-encoded rRNAs. In addition to tRNA and rRNA, mitochondrial DNA also encodes 13 proteins for the inner mitochondrial membrane respiratory chain complex. The mitoribosome is responsible for the synthesis of these 13 proteins. Thus, mutations or defects of MRPs or other translation tools can cause mitochondrial diseases.