Communication disorder is a widespread disabling problems and associated with adverse, long term outcome that impact on individuals, families and academic achievement of children in the school years and affect vocational choices later in adulthood. The aim of this study was to determine prevalence of speech disorders specifically stuttering, voice, and speech-sound disorders in primary school students in Iran-Yazd. In a descriptive study, 7881 primary school students in Yazd evaluated in view from of speech disorders with use of direct and face to face assessment technique in 2005. The prevalence of total speech disorders was 14.8% among whom 13.8% had speech-sound disorder, 1.2% stuttering and 0.47% voice disorder. The prevalence of speech disorders was higher than in males (16.7%) as compared to females (12.7%). Pattern of prevalence of the three speech disorders was significantly different according to gender, parental education and by number of family member. There was no significant difference across speech disorders and birth order, religion and paternal consanguinity. These prevalence figures are higher than more studies that using parent or teacher reports.