Abstract： Objective To measure the paraquate (Pq) levels in urine and serum of patients with sodium dithionite in order to predict the outcome of patients after paraquart intoxication. Method Standard colorimetry and standard curve for paraquat measurement was established using sodium dithionite to react with paraquat in dif-ferent concentrations and in alkaline medium.Twenty-two patients with paraquat poisoning were admitted from Jan-uary 2008 to May 2009. Serum and urine samples of these patients were collected. The paraquat concentrarions in the serum and urine samples were semi-quantitatively and quantitatively determined with the methods as mentioned. The relationships between the outcome of patients and the levels of Pq in the urine and serum samples were ana-lyzed. Results Six (27.3%) of the 22 patients survived after hemoperfusion, plasma exchange, and hemofiltra-tion therapies, and were followed up for over 3 months. According to our colorimetry for the detection of paraquat,urine samples from 6 survivals showed very light color in 3 patients and light color in as many. The urine samples from the 16 died ones showed light color in one patient, moderate color in 2, dark color in 2 and very dark color in 11 patients. The mean concentrations of paraquat in urine samples of 6 survivals and 16 died patients were (1.95 ±1.76) mg/Land (53.4±45.9) mg/L, respectively (P ＜0.0l). The mean concentrations of paraquat in serum sample of 6 survivals and 13 died ones were (1.70 ± 1.39) mg/L and (29.5 ± 22.1) mg/L, respective (P ＜0.01). The outcomes of these patients were closely related to semi-quantitative values of urine samples (is:-0.804, P ＜ 0.01), quantitative values of urine samples (rs: -0.772, P ＜0.01), and quantitative values of serum samples (rs:-0.593, P ＜ 0.01). Conclusions Alkaline sodium dithionite can be used for the rapid determination of paraquat in urine and serum. Theses measurements can serve as predictors of outcome of patientswith paraquat intoxication.