First void urine samples were collected from 24 residents in an area of past intense mining and smelting activity of arsenical ores. Seven samples were also taken from a control village. The arsenic species in the urine were separated and quantified with an HPLC-ICP-MS system equipped with a hydraulic high-pressure nebulizer. The detection limit for arsenic in urine using this system is 0.05 microgram dm-3. Creatinine was also determined for all samples to remove the influence of urine density and all results were expressed in microgram As g-1 creatinine. The results showed elevated levels of both organic and inorganic arsenic compounds in the 'exposed' population's urine when compared with those of the control group. The total As concentrations (less arsenobetaine) in the 'exposed' population were in the range 2.7-58.9 micrograms g-1 creatinine (mean 13.4, median 9.2 micrograms g-1) compared with the control group data range 2.5-5.3 micrograms g-1 (mean 4.2, median 4.7 micrograms g-1).