Background: The early diagnosis of elevated intracranial pressure (ICP) improves the prognosis of acute liver failure (ALF). Invasive monitoring (intracranial bolts) is the gold standard approach for measuring ICP, however it comes with problems. Objective: This study aimed to evaluate the role of bedside, ultrasound (US) guided measurement of optic nerve sheath diameter (ONSD) in ALF children. Methods: 36 ALF and 21 healthy children (0‐18 years) were enrolled. All patients had undergone full history taking, thorough clinical examination, and routine investigations. ONSD was measured for each on admission, with any change of consciousness and at recovery in ALF, and once in controls. Results: Both groups were age- and sex-matched. The ALF group showed significant increase in ONSD than in healthy controls (P 0.008). On admission, the mean of ONSD in resolved group (4.13 ± 0.573 mm) was lower than that of died group (4.57 ± 0.64 mm) but without statistical significance (P = 0.082). ONSD before discharge significantly increased in died group 5.07 ± 0.44 mm than in living group (3.98 ± 0.354 mm, P<0.0001). ONSD was significantly higher in ALF patients with disturbed conscious level (5.16 ± 0.45 mm) than in conscious patients (4.007 ± 0.34 mm, P <0.0001). ONSD at a cut-off value of > 4.82 mm showed accuracy of 88.7% in discriminating between resolving and vanishing ALF patients (P =<0.0001). Conclusions: ONSD is a safe bedside method that may be used to serially monitor children with ALF. It is an excellent predictor of patient outcomes.