OBJECTIVE: To evaluate the efficacy and safety of sodium dimercaptopropane sulfonate( DMPS) in the treatment of patients with increased urinary mercury. METHODS: By random sampling method,68 patients with elevated urinary mercury were chosen as study subjects. Among them,61 cases were observation subjects working with mercury and 7 cases were chronic occupational mild mercury poisoning. DMPS was used to eliminate mercury by intramuscular injection. The changes of urinary mercury level were observed before and after treatment,and the curative effect was analyzed. RESULTS: The median( the 25 th and 75 th percentiles) of natural voiding urinary mercury was 36. 6( 28. 4,55. 6) μmol / mol creatinine and 24 hours total urine mercury amount was 1 074. 7( 608. 0,1 646. 3) μg / d in the first course of treatment.After 1 to 8 courses of mercury expulsion,the 24 hours total urine mercury amount in 68 patients were lower than the normal reference level( 45. 0 μg / d). The median( the 25 th and 75 th percentiles) of one-time morning urinary mercury level before hospital discharge was 2. 7( 1. 8,4. 0) μmol / mol creatinin,which was lower than the level of natural voiding urinary mercury( P < 0. 05). The first and second course of treatment resulted in the highest decline in urinary mercury,followed by a gradually decreased in urinary mercury in later courses. The number of treatment courses in observation subjects working with mercury was less than that in patients with chronic mild mercury poisoning [( 4. 0 ± 1. 3) vs( 5. 6 ±1. 1) times,P < 0. 05]. There was a positive correlation between the number of treatment courses and the level of natural voiding urinary mercury or 24 hours total urine mercury amount in the first course of treatment( P < 0. 01). The number of courses of mercury expulsion was not related to gender,length of service and age( P > 0. 05). One patient had dizziness and pale after intramuscular injection of DMPS,the symptom was disappeared with symptomatic treatment; 68 patients after treatment have no other adverse reactions. CONCLUSION: Using DMPS as mercury displacement treatment was effective and relatively safe. The change of urinary mercury after DMPS treatment can be used as a basis for establishing clinical standard for patients with increased urinary mercury.