Pain, agitation and delirium (PAD) are the most common problems encountered in adult critically ill and mechanically ventilated patients in an Intensive care unit (ICU). Prolonged delirium, a manifestation of brain dysfunction, is one of the strongest independent predictors (risk factors) of mortality, morbidity, increased length of stay and cost of care in ICU. Prevention of delirium may improve the outcome. Pain evokes a stress response. Adequate analgesia (with opioid and adjuvants) and sedation is helpful in prevention of agitation and stress induced reactions. Routine pain assessment and reassessment is essential for appropriate treatment. Most ICU patients suffer with agitation and anxiety which can adversely affect the clinical outcomes. To counteract the agitation, sedation is commonly used. It is prudent to promptly diagnose and treat possible underlying cause of agitation. Delirium is a major health problem in critically ill and mechanically ventilated ICU patients with an incidence varying from 16% to 89%.