Delirium is a kind of fluctuating cognitive impairment that occurs during a short time. Early detection of delirium leads to acceleration the treatment. There are many tools for identifyingand screening of delirium. This study aimed at comparing the advantages and disadvantages of the various tools used for diagnosing delirium, their validity and accuracy and the way they are used by physicians or nurses.In this review article, available databases including Pubmed, Medline, Science Direct, ProQuest, SID, Google Scholar was assayed by keywords such as delirium assessment, delirium tools, cognitive disorder and nurse, nurse and delirium. Among the 55 articles found from 1990 to 2012, 15 relevant articles included the study.A review of the related studies showed that the most common screening tools for delirium, which can be used by different person, were CAM, CAM-ICU, NeeCham, ICDSC, DSI, CTD, DOS, Nu-DESC.Each of these tools enjoys different levels of validity and reliability and can be used in different patients.Related articles in relation to diagnosis of delirium in nursing practice were limited. However, two questionnaires namely CAM-ICU and NeeCham were found to be more applicable for critically ill patients and enjoy a higher sensitivity and specificity with regard to other tools. Findings indicated that NeeCham questionnaire can be easily used by the nurses on the patient's bedside during daily activities and can even detect the susceptible patients sooner.