Acute adrenal insufficiency is a dangerous complication with hogh risk of death in congenital adrenal hyperplasia (CAH) patient. This study was studied some clinical features of acute adrenal tnsufficiency in 52 patients with CAH at the Endocrinology - Metabolism - Genetic Department of National Hospital of Pediatrics from 01/01/2006 to 31/12/2010. Results showed first clinical signs that presented at 1 - 2 weeks of age accounted for 44.2 percent. Disease that was diagnosed after 4 weeks of age accounted for 63.5 percent. The hospitalized causes were vomiting (84.6 percent), diarrhea (23.1 percent). The most commonly misdiagnosed was pneumonia (32.6 percent) and malnutrition (30.2 percent). 100 percent of patients with adrenal insufficiency had moderate and severe dehydration, vomiting (98.1 percent), 65 percent of patients with lost weight. 26.9 percent of patients having acute adrenal failure accompanied with bacterial infections, including pneumonia (19.2 percent). In conclusion, often diagnosed late, after 4 weeks of age disease was accounted for 63.5 percent with atypical clinical symptoms as moderate and severe dehydration (100 percent), lost weight (100 percent), vomiting (98.1 percent). Shock was seen with a high rate (23.1 percent).