An enrichment method is described for the determination of nickel in urine by flame atomic absorption spectrometry after preconcentration with ammonium pyrrolidine dithiocarbamate on activated carbon. The recoveries are above 90 %. The factors affecting recoveries, such as pH, amounts of activated carbon and complexing reagent, and the contact times, were also studied. The calibration graph was rectilinear for the range 2.4-80 mu g l(-1). The relative standard deviation of the measurement was 3 % for nickel at a concentration of 20 mu gl(-1) (n=9). The detection limit of the method was 0.75 mu g l(-1) when 500 ml urine was used.