Purpose: Acute acetaminophen intoxication is a common occurrence that can cause lethal complications. In most domestic emergency departments, clinicians tend to treat acetaminophen intoxication based on patients' history alone, simply due to the lack of a rapid acetaminophen laboratory test. We performed a 20-month study of intoxication patients to determine the correlation between the history of patients and serum laboratory tests for acetaminophen. Methods: We took blood samples from 280 intoxication patients to evaluate whether laboratory findings detected traces of acetaminophen in the sample. Patients were then treated according to their history. Laboratory results came out after patients' discharge. Agreement between patients' history and laboratory results were analyzed. Results: Among the 280 intoxicated patients enrolled, 38 patients had positive serum acetaminophen concentrations; 18 out of 38 patients did not represent a history suggesting acetaminophen intoxication. One patient without the history showed toxic serum acetaminophen concentration. Among the patients with the history, two patients with toxic serum acetaminophen concentration did not receive N-acetylcysteine (NAC) treatment due to their low reported doses, while other 2 patients without significant serum acetaminophen concentration did receive NAC treatment due to their high reported doses. Conclusion: This study showed a good overall agreement between history and laboratory test results. However, some cases showed inconsistencies between their history and laboratory test results. Therefore, in treating intoxication patients, a laboratory test of acetaminophen with rapid results should be available in most domestic emergency departments.