A mosaic pattern of striatal pathology is described in a male who developed severe generalised dystonia from the age of 10 years, and died at the age of 18 years. There was no family history of dystonia, and extensive investigations during his life failed to identify a cause for the dystonia. The caudate nucleus and putamen showed a network of cell loss and gliosis surrounding islands of preserved striatum. Dorsal parts showed confluent gliosis, and ventral parts were spared. The pattern suggested a correlation with patch-matrix organisation, but there was no correlation with the distribution of calbindin immunoreactive cells, which are present in the matrix of the classical striosome-matrix organisation. The pathological findings were unlike those in status marmoratus, perinatal hypoxia-ischaemia, Huntington's disease, and neuroacanthocytosis, but similar to those reported in a 44-year-old man with predominantly cranial dystonia.