Exposure to nickel was evaluated on the base of nickel in urine concentration (Ni-U) in 649 persons both adults and pre-school and school children; 241 persons were occupationally exposed in steel-mill and rolling-mill. Environmentally exposed groups consisted of inhabitants of industrial and rural towns. The occupationally exposed groups showed Ni-U mean concentrations amounted to 25.7, 18.1, 15.9, and 15.7 micrograms/m3. In environmentally exposed groups of adults, Ni-U concentrations were almost equal to those in persons inhabiting industrial and rural areas-7.8 and 7.7.micrograms/dm3, respectively. Ni-U concentrations in children groups were more differentiated 8.5 and 9.2 micrograms/dm3 in rural area and 9.9 and 10.6 micrograms/dm3 in industrial area. The recommended mean group allowable Ni-U concentrations for occupational exposure amounts to 12 micrograms/dm3 and for environmental exposure 2.7 micrograms/dm3. In view of the above mentioned Ni-U allowable values it is evident that there exist significant occupational exposure and elevated environmental exposure in the defined percent of the investigated population.