Alexander disease (AD), a rare neurodegenerative disorder of the central nervous system, is characterized by the accumulation of cytoplasmic protein aggregates (Rosenthal fibers) composed of glial fibrillary acidic protein (GFAP) and small heat-shock proteins within astrocytes. To date, more than 40 different GFAP mutations have been reported in AD. The present study is aimed at the molecular diagnosis of Italian patients suspected to be affected by AD. By analyzing the GFAP gene of 13 unrelated patients (eight with infantile form, two with juvenile form and three with adult form), we found 11 different alleles, including four new ones. Among the novel mutations, three (p.R70Q, p.R73K, and p.R79P) were identified in exon 1 and p.L359P in exon 6. The sequence analysis also detected six different single nucleotide polymorphic variants, including two previously unreported ones, spread throughout non-coding regions (introns 2, 3, 5, 6, and 3'UTR) of the gene. All patients were heterozygous for the mutations, thus confirming their dominant effect.