Introduction: Delirium is common in critically sick patients and related prolonged length of medical intensive care unit (ICU) and long-run psychological impairment. Aim of the study: The aim of the study is to assess the incidence of delirium in critically ill patients. Evaluate the effectiveness of diagnosing delirium by subjective global assessment compared to CAM-ICU score in critically ill patients. Evaluate the effect of haloperidol versus atypical antipsychotic drugs in the treatment. Methods: Total 200 critically ill patients selected sequentially on their admission to ICU and subjected for full medical history taking, clinical examination daily with emphasis on full neurological assessment, daily assessment of delirium along their stay in the ICU by 2 methods: subjective global assessment which is the subjective individual clinical impression performed by the attending resident in the ICU. CAM-ICU score which is performed by the physician in charge of the study using CAM-ICU worksheet. Results: Delirium is a frequent complication in the intensive care unit. The CAM-ICU scoring system appears to be rapid, valid, and reliable for diagnosing delirium in the ICU setting and may be a useful instrument for both clinical and research purposes. Use of objective criteria may identify patients mistakenly thought to have delirium who do not meet objective criteria for the diagnosis of the condition. The degree of agitation is an essential indicator of the dosage of the used antipsychotic drug, need for additional antipsychotics. Conclusion: Delirium is a common problem in critically ill patients and is not easy to manage.