Background:   Management and assessment of pain in patients in critical care unit is a daily challenge for the health care professionals, particularly in the intubated patients, patients on mechanical ventilation, or patients who are on analgesia as such patients are unable to self-assess existence and intensity of pain. It is crucial for physicians to follow guidelines that help in pain assessment and management effectively. Aim of the work: Our aim in this study was to study how to evaluate and manage pain in an intensive care unit patient, predominantly those patients who are unable to self- report or assess. Materials and methods: We conducted this review using a comprehensive search of MEDLINE, PubMed, and EMBASE, January 1994, through March 2017. The following search terms were used: pain in ICU, pain management in ICU, pain assessment methods, pain assessment in intubated patients. Conclusion: Physical clues, which are given by comatose and intubated patients in critical care unit, should be taken in consideration, as they can be used as a method to identify existence of pain, and must be followed by effective management to decrease discomfort and prevent acute and chronic adverse effects.