Wolfram syndrome (WS) is an autosomal recessive disorder caused by mutations in WFS1 gene. The clinical features include diabetes insipidus, diabetes mellitus (DM), optic atrophy, deafness, and other variable clinical manifestations. In this paper, we present the clinical and genetic characteristics of 3 WS patients from 3 unrelated Turkish families. Clinical characteristics of the patients and the age of onset of symptoms were quite different in each pedigree. The first two cases developed all symptoms of the disease in their first decade of life. The heterozygous father of case 2 was symptomatic with bilateral deafness. The first ocular finding of one patient ( patient 3) was bilateral cataract which was accompanying DM as a first feature of the syndrome. In this patient's family, there were two members with features suggestive of WS. Previously known homozygous mutations, c.460 + 1G > A in intron 4 and c.1885C > T in exon 8, were identified in these cases. A novel homozygous c.2534T > A mutation was also detected in the exon 8 of WFS1 gene. Because of the rarity and heterogeneity of WS, detection of specific and nonspecific clinical signs including ocular findings and family history in non-autoimmune, insulinopenic diabetes cases should lead to a tentative diagnosis of WS. Genetic testing is required to confirm the diagnosis.