Two indicators (Risk score and Resection Index) for pulmonary and cardiac complications after lung resection were evaluated on 182 patients with bronchogenic carcinoma by quantita-tive technetium 99m macroaggregation albumin (MAA) perfusion scanning preoperatively and who then underwent lung resection. After surgerg, the correlations between preoperative lung function and the development of postoperative pulmonary and cardiac complications (PPCC) were examined in each case. The Risk score consisted of eight parameters (% FVC, FEV 1.0%, % MVV, % MMF, V50/HT, V25/HT, % peak flow, and % DLco), and a value of from 0 to 8 was assigned. In the patients with a Risk score of 0, PPCC occurred in 5 of the 71 cases, while complications were noted in 26 of the 94 patients with a Risk score from 1 to 5 and in 14 of the 17 patients with a score of over 6. The Resection Index was calculated from the predicted postoperative FEV 1.0 from the quantitative 99m Tc MAA perfusion scan and the predicted FEV 1.0, PPCC occurred in 20 of the 27 patients with a Resection Index of below 40%, 25 of the 131 patients with an index of 40% to 65%, and none of the 24 with an index over 65%. Both indicators had a good correlation with the occurrence of PPCC. These two indicators, the Risk score and the Resection Index, were clincally useful for predicting PPCC preoperatively and may help reduce the incidence of PPCC.