Background Dentatorubral‐pallidoluysian atrophy is a hereditary neurodegenerative disease prevalently reported in Japan but rare in Caucasians. The objective of this study was to reconstruct the pedigree of Italian dentatorubral‐pallidoluysian atrophy familial cases describing their clinical features. Methods We investigated 6 apparently unrelated dentatorubral‐pallidoluysian atrophy families comprising a total of 51 affected individuals: 13 patients were clinically examined, and for 38 patients clinical data were collected from clinical sources. The dentatorubral‐pallidoluysian atrophy diagnosis was genetically confirmed in 18 patients. Genealogical data from historical archives were analyzed. Results All 6 families were unified in a large pedigree deriving from a founder couple originating from Monte San Giuliano (Italy) in the late 1500s, with 51 affected subjects over the last 4 generations. Wide phenotypical variability in age at onset and clinical features was confirmed. Epilepsy was more frequent in juvenile cases than in late adults, with cognitive/psychiatric and motor disorders observed regardless of age at onset. Conclusions We have described the largest Caucasian dentatorubral‐pallidoluysian atrophy pedigree from a single founder couple. The introduction of the dentatorubral‐pallidoluysian atrophy gene in Italy could have arisen as a result of trade relationships between the Spanish or Portuguese and the Japanese in the 1500s. © 2019 International Parkinson and Movement Disorder Society