Purpose: In this article, the process of clinical interview with mentally retarded children will be investigated. Method : To get the purpose, the main problems in clinical interview with mentally retarded children and its stages are presented. In this paper, the communicative methods which facilitate the relation between the interviewer and the mentally retarded children will be discussed and the methods of direct an indirect obsrervation used in interview and the relavant instruments will be introduced.  At the end, the principles of interviewing with the mentally retarded children and its usages are expressed. Findings and Conclusions: Behavioral and psychological problems in mentally retarded children nececciates a standardized interview. Therefore faced with mentally retarded children, the interviewer should be prepared psychologically. He should utilize advanced instruments for interview, observation and gathering the information.