Purpose: We investigated comparison of clinical characteristics and prognosis by initial endoscopic severity in caustic injury and then discussed predisposing factors which can be helpful in predicting the prognosis and determining the treatment. Methods: This study was a retrospective review of medical records from patients over the age of 15, who underwent initial endoscopy for caustic injury from April 2007 through November 2014. Patients were classified according to two groups based on the initial endoscopic finding by Zargar's classification: patients with grade 0, I, IIa at esophagus (low risk group) and patients with grade IIb, IIIa, IIIb at esophagus (high risk group). The two groups were then compared. Results: A total of 55 patients were included (low risk group [n=44] vs. high risk group [n=11]). Old age (p<0.001), large amount of ingestion (p<0.05), oropharyngeal symptoms (p<0.01), high SOFA score (p<0.001), high WBC count (p<0.05), low base excess (p<0.01), and HCO3 (p<0.05) were statistically significant factors in the high risk group. A poor prognosis was observed for hospital stay (p<0.001), ICU admission (p<0.001), mortality (p<0.01), and stricture (p<0.001) in the high risk group. Conclusion: Clinical characteristics including age, amount of ingestion, oropharyngeal symptoms, SOFA score, WBC count, base excess, and $HCO_3$ can be helpful in the decision to undergo initial endoscopy and risk assessment by initial endoscopic severity can be helpful in predicting prognosis and determining the treatment plan.