Objective. We aimed to determine clinical and laboratory findings that were different between those patients who died and those who survived and to look for factors associated with the mortality in amatoxin-containing mushroom poisoning. Methods. The mushroom poisoning patients who were admitted to our clinic between 1996 and 2009 were retrospectively evaluated. The diagnosis was based on a history of mushroom ingestion, clinical picture and the presence of serum alpha-amanitin. Patients were divided into two groups as the survival group and the fatality group. Clinical and laboratory findings were compared between the two groups. Relation between variables and clinical outcome was analyzed. Results. A total of 144 amatoxin poisoning patients were included in this study. Patients who died were more likely to have demonstrated low mean arterial pressure, encephalopathy, mucosal hemorrhage, oliguria-anuria, hypoglycemia, and thrombocytopenia during the hospitalization. Low sodium values and high urea, AST, ALT, total bilirubin, LDH, prothrombin time, international normalized ratio, and activated partial thromboplastin time values were associated with increased likelihood of mortality. Nineteen patients developed acute renal failure. Fourteen patients developed acute hepatic failure. All the 14 patients who died developed acute hepatic failure. The mortality rate was 9.7%. Conclusions. The factors associated with mortality determined in this retrospective study may be helpful for clinical outcome assessment and monitoring of patients with amatoxin-containing mushroom poisoning.