The most common causes of speech development disorders (SDD) were established, along with the types of professional help these patients received. Their speech progress was also assessed with respect to individual causes for the developmental delay. This retrospective study included 101 children (30 girls and 71 boys) who were managed for SDD for the first time at a phoniatric outpatient clinic during the period from 1990 to 1997. The possible causes of the disorder were summarized from the medical documentation (files). A questionnaire was sent to all parents having children with such disorders with questions on the types of professional help they had received and speech progress in their children. The completed questionnaires and the patients’ medical files were used to assess speech progress after over one year. The most common causes of SDD were: central nervous system disorders and injuries (38.6%), mental development disorders (20.8%) and hereditary disorders (18.8%); 57.4% of the children had several causes of SDD. The highest percentage of children was helped by a speech therapist (89.9%), 52.6% of children received help from a psychologist, and 32.9% from a special pedagogue. Out of 63 children for whom data on speech development were received after over one year of professional help, 7.9% made no progress in their speech, 66.67% made some progress but did not catch up with their peers, and 25.4% of them managed to catch up with their peers in terms of speech development. Children with hereditary causes of speech impairment showed the greatest progress and those with mental development disorders and diseases or injuries of the central nervous system showed least progress. Among all causes of SDD in these children, there were 21.8% cases of premature birth and 5.9% cases of small for gestational age (SGA) children. The most common causes of SDD are diseases or injuries to the central nervous system and mental development disorders. In spite of multiple treatment modalities, less than one quarter of these children catch up with their peers in terms of speech development, while two thirds do make progress but never catch up with their healthy peers. The best prognosis concerning speech development is seen in children with hereditary disorders, and the worst in those with diseases or injuries to the central nervous system. The detection and appro priate management of children with SDD should begin as soon as possible, if possible during the development of speech centres and pathways within the central nervous system.