Abstract: Objective To report the clinical features, diagnosis, management and evaluation of the outcome of a patient with secondary thallium poisoning. Methods The patient was a 42-year-old female who had experienced abdominal pain with elevated blood amylase and lipase as the first symptom. She was diagnosed with acute pancreatitis in the local hospital and the symptoms relieved after treatment. One month later, she developed abnormal mental behavior rapidly and severe Guillain-Barre syndrome turned up gradually. Thallium concentration significantly elevated in the blood and urine, which led to the diagnosis of Thallium poisoning. After reviewing of retrospective clinical history of this case and related literature, we suspected that she experienced thallium poisoning for the second time. So far as we know, this was the first report about people experienced thallium poisoning two times in one month. Results This case was confirmed by urinalysis, and the symptom of patient improved slowly after active treatment. Conclusion When a person experiences alopecia, peripheral neuropathy and gastrointestinal disorders in a short time, it is reasonable to consider the possibility of thallium poisoning.