Mitochondrial diseases, taking into account those that affect the processes of the respiratory chain (RC) and mitochondrial oxidative phosphorylation system (OXPHOS), make up a relatively frequent group within rare diseases that usually have multisystem involvement, a very variable phenotypic expression and a complex genetic base. Renal involvement is uncommon, with the tubule being the most affected, specifically its proximal portion, developing into full Toni-Debré-Fanconi syndrome in the most serious cases. However, in some cases the glomerulus is involved, fundamentally in focal segmental glomerulosclerosis form (FSGS), expressed by proteinuria and renal failure. It is important that the Nephrologist keeps in mind the possibility of a mitochondrial disease in patients with this type of renal involvement that present clinical data with these characteristics, especially diabetes mellitus and deafness. In cases with FSGS, a correct diagnosis will avoid the inappropriate use of immunosuppressive medication. Specific treatments do not exist for the majority of mitochondrial diseases, but it is likely that the intense research that currently exists for these diseases will eventually produce effective treatment possibilities.