This article reviews purposes and types of diagnostic reports and provides guidelines for report writing. Report writing varies greatly depending upon the examination itself and the clinician's style of reporting. Such variation is acceptable as long as professional standards are maintained. The basic guidelines of report writing are: (1) the organization should provide for easy retrieval of specific information; (2) the terms and categories should be free of ambiguity; and (3) only terms in common use by professional should be used. Lack of uniformity, bad writing, inappropriate terminology, and overstatements are the basic problems of report writing that may be overcome through practice, study of sample reports, and courses in report writing.