Hereditary diffuse leukoencephalopathy with axonal spheroids (HDLS) is an autosomal dominant disorder characterized by white matter neurodegeneration, progressive cognitive decline, and motor symptoms. Histologically, it is characterized by axonal swellings ("spheroids"). To date, over 20 different mutations affecting the tyrosine kinase domain of the protein have been identified in the colony stimulating factor 1 receptor (CSF1R) gene. Our goal is to describe three unrelated Italian patients affected by HDLS and carrying new CSF1R mutations, thus expanding the mutational spectrum and phenotypic presentation. CSF1R gene analysis was performed in 15 patients (age range 25-83 years) with undefined leukoencephalopathy and progressive cognitive decline. In three patients (two males and one female, aged 58, 37, and 48 years, respectively), new heterozygous missense mutations affecting the protein tyrosine kinase domain of the CSF1R gene were detected. In all of these patients, behavioural and cognitive changes were preceded by an ischemic stroke-like episode. A positive family history was present in only one case.