We compared the usefulness of single-photon emission computed tomography/computed tomography (SPECT/CT) and lung perfusion scintigraphy (LPS) for predicting postoperative lung function by comparing patients with borderline lung function. A total of 274 patients who underwent simultaneous LPS and SPECT/CT and had a forced expiratory volume in 1 s (FEV1) or diffusing capacity for carbon monoxide (DLCO) under 80% were included. The % uptake by LPS was calculated by the posterior-oblique method. The concordance and difference of the % uptake, predicted postoperative (ppo) FEV1 and ppoDLCO as determined by 2 methods were evaluated. The association between ppo values and actual postoperative FEV1 and DLCO was examined. Subgroup analysis was conducted in redo-operation cases. The % uptake of each lobe, except the right middle lobe, showed fair concordance (concordance correlation coefficients for right upper, middle, lower, left upper and lower lobe = 0.61, 0.37, 0.71, 0.66 and 0.69, respectively). ppoFEV1 and ppoDLCO also revealed high concordance between both methods (concordance correlation coefficient = 0.93 for ppoFEV1 and concordance correlation coefficient = 0.92 for ppoDLCO) without a significant difference (P = 0.42 for ppoFEV1; P = 0.31 for ppoDLCO). Both ppoFEV1 and ppoDLCO showed a significantly high correlation with the actual FEV1 (r = 0.77, P < 0.01 for LPS, r = 0.77, P < 0.01 for SPECT/CT) and DLCO (r = 0.62, P < 0.01 for LPS, r = 0.62, P < 0.01 for SPECT/CT). High concordance of % uptake, ppoFEV1 and ppoDLCO was present in redo-operation patients. Both LPS and SPECT/CT showed high predictability for actual postoperative lung function, and LPS showed good performance to estimate ppoFEV1 and ppoDLCO with reference to SPECT/CT, even in redo-operation cases.