Prospectively gathered information in the Ontario Cancer Foundation's computerized clinical database was analysed to provide a description of the management of 12,399 patients with unresected non-small cell lung cancer (NSCLC) registered at seven regional cancer centres in Ontario between 1982 and 1991. Overall, 44% received initial thoracic radiotherapy, 19% received initial radiotherapy to metastatic sites, and 36% received no immediate radiotherapy. Of those who received thoracic radiation 41% received doses > or = 40 Gy and 59% received doses < 40 Gy. Among the seven centres, the proportion of patients receiving initial thoracic radiotherapy ranged from 41% to 56% (p < 0.001), and the proportion of those receiving doses > or = 40 Gy ranged from 30% to 68% (p < 0.001). Between 1982 and 1991, the overall proportion of patients who received initial thoracic radiotherapy decreased from 48% to 38%, the proportion of those receiving high dose treatment decreased from 55% to 28%, and the mean number of fractions given to the chest decreased from 17 to 10. Only 10% received chemotherapy at any time, and that proportion ranged from 3% to 21% (p < 0.001) among the seven centres. Between 1982 and 1991 the proportion of patients receiving chemotherapy decreased significantly from 15% to 8% (p < 0.001) across the Cancer Foundation as a whole. These wide variations in management policies were not associated with any significant differences in survival, which was similar at all seven centres, and remained constant between 1982 and 1991.