Frontotemporal dementia (FTD) is the second most common cause of young onset dementia after Alzheimer's disease. FTD presents with progressive changes in behavior, personality and language deficits and it is a clinically, pathologically and genetically heterogeneous disorder. Histopathological heterogeneity includes various intraneuronal inclusions, mostly positive for tau or ubiquitin, with TDP-43 positive, and more rarely FUS positive. About 30-50% of FTD patients are familial with an autosomal dominant pattern of inheritance. Mutations in a number of genes are associated with FTD, most commonly in MAPT or GRN genes, and in the C90RF72, and more rarely in VCP, TARDBP or FUS. Recently, a new pathological classification of FTD was developed according to the precipitate proteins denoted frontotemporal lobe degeneration (FTLD) including FTLD-Tau, FTLD-TDP43, FTLD-FUS, FTLD-UBS and more. There is a correlation between the clinical type and pathological findings and this correlation is important for understanding the mechanism as well as the intervention. Unfortunately, there is no effective treatment for FTD but we hope that recent developments will make advances towards finding effective therapy.