STUDY OBJECTIVE--To review the incidence of leukaemia and non-Hodgkin's lymphoma in children and young adults in the area less than 25 km from the Dounreay nuclear installation and the remainder of the Kirkwall postcode area in the full time period for which data are now available (1968-91), and to determine whether the excess incidence reported in the period up to 1984 has continued in subsequent years. DESIGN--Geographical incidence study. SETTING--The Kirkwall postcode area of Scotland. SUBJECTS--Children and young adults resident in the area in the period 1968-91. MAIN RESULTS--Observed numbers of cases of leukaemia and non-Hodgkin's lymphoma and observed to expected ratios with expected numbers based on Scottish national rates were determined. In 1968-91, 12 cases were observed compared with 5.2 expected in the zone