It is imperative that the surgeon promptly determine the severity of any acute injury of the upper gastrointestinal (UGI) tract by caustic material ingested and the definite therapy be instituted. Prognostic factors of such injuries have not been clearly demonstrated in previous reports. Here, some prognostic factors and recommended emergency surgical indications in clinical assessment are discussed.Forty-six patients (22 men and 24 women; age range 19 to 77 years), sustaining acute corrosive injuries to the UGI tract, were retrospectively assessed from November 1990 to May 1993. Immediate management was given to prevent shock, to identify any associated injury and to observe patency of the airway. Emergency operation was performed if any signs of peritonitis, mediastinitis or sepsis were present. Age, sex, time interval between ingestion and initial resuscitation, consciousness, peritoneal sign, shock index, pH value and [HCO3-] in arterial blood gas were evaluated as prognostic factors with respect to mortality. Chi-square test with Yates' correction was used. A p value less than 0.05 was regarded as statistically significant.Suicide attempt by caustic ingestion was in 40 patients (87%) and ingestion was accidental in 6 (13%). Acidic injury was specified in 36 patients (78.3%). In 14 severely injured patients, emergency exploratory laparotomy with or without esophagogastrectomy was performed in 9 (19.6%), of whom 2 survived. The other five patients were treated conservatively, and all died. Overall mortality rate was 26.1% (12/46). A significantly higher mortality rate was observed in patients with age > or = 50 years, positive peritoneal sign, shock index > 1, pH below 7.2 and bicarbonate concentration below 16 mEq/L as revealed by arterial blood gas (p < 0.05).The prognostic factors related to a higher mortality rate included age 50 years old or more, positive peritoneal sign, shock index above 1, pH below 7.2 and [HCO3-] below 16 mEq/L in arterial blood gas. Recognition of these factors indicates further detailed study will be required to propose a caustic injury score for predicting severity. Nevertheless, emergency operation is recommended if there are positive signs of peritonitis or mediastinitis, shock index above 1, pH below 7.0 and [HCO3-] below 10 mEq/L in arterial blood gas.