Objective. To examine the utility of arterial blood gas analysis (ABG) in early evaluation of prognosis in paraquat poisoning. Methods. Our aim was to summarize the case data of 138 patients poisoned with oral paraquat treated in the Emergency Department of 307 Hospital of the Chinese People's Liberation Army from June 2009 to Sept. 2010, and analyze the correlations between various indices of arterial blood gas analysis (including pH, PO₂, PCO₂, base excess [BE], HCO₃⁻) to prognosis and blood PQ concentration of patients presenting within 24 h after taking paraquat. Results. PCO₂, HCO₃⁻ and BE values in deceased patients were significantly lower than those in surviving patients, p values 0.0003, <0.0001, <0.0001; PCO₂, HCO₃⁻ and BE values in patients who died in < 3 d were significantly lower than those in those who died in 3–7 d and 7 d after taking paraquat (p < 0.0001). The results of Cox Regression Analysis showed that there was correlation between paraquat amount, blood paraquat concentration and BE values and patients’ survival time; the larger the absolute BE value was, the higher the death rate. Nevertheless, there were no correlations between early pH or PO₂ and prognosis in these patients. Conclusion. BE values may be a reliable index in early evaluation of prognosis in paraquat poisoning.