Background and Aim: Specific language impairment (SLI) is one of the most prevalent developmental language disorders which is less considered in Persian researches. The aim of this study was to investigate the differences in some morpho-syntactic features of speech and other language skills between Persian children with specific language impairment and their normal age-matched peers. Moreover, the usefulness of the test of language development-3 (TOLD-3), Persian version, as a tool in identifing Persian-speaking children with this impairment, was investigated.
Methods: In a case-control study, the results of the test of language development and speech samples analysis of 13 Persian-speaking children (5 to 7 years old) with specific language impairment were compared with 13 age-matched normal children.
Results: The results of this study showed that there were significant differences between the scores of specific language impairment group and control group in all measured aspects of the TOLD-3 (p<0.001) the children with specific language impairment had a shorter mean length of utterance (p<0.001) and made less use of functional words in their speech (p=0.002) compared with their peers.
Conclusion: Such as specific language impairment children in other languages, all language abilities of Persian-speaking children with specific language impairment are less than expected stage for their age. Furthermore, the Persian version of TOLD-3 is a useful assessment instrument in identifying children with specific language impairment which is comparable to the

Background and Aim: Specific language impiarment (SLI) is one of the most prevalent developmental language disorders its diagnosis is a problematic issue among researchers and clinicians because of the heterogeneity of language profiles in the affected population and overlapping with other developmental language disorders. The aim of this study was to review the suggested diagnostic criteria for this disorder, controversies about these criteria and identify the most accurate diagnostic methods.

Methods: Published article from 1980 to 2012 in bibliographic and publisher databases including Pubmed, Google scholar, Cochran library, Web of Science, ProQuest, Springer, Oxford, Science direct, Ovid, Iran Medex and Magiran about the diagnostic methods for discriminating preschoool children with specific language impiarment from normal developing children were reviewd in this article. These keywords were used for research: “specific language impairment”, “SLI”, “diagnosis or identification”, “standardized tests”, and “tests for language development”.

Conclusion: The results of this study show inspite of agreement of researchers and clinicians about exclusionary criteria as one basic part of the diagnosis of specific language impiarment , there is no consensus about the other part, inclusionary criteria. Different studies used different inclusionary criteria which can be divided to categories of clincal judgment, discrepancy-based criteria, standardized testing, clinical markers and markers from spontaneous speech samples. Advantages, disadvantages, and clinical applicability of each diagnostic method are discussed in this article.