Objective: The aim of this study was to evaluate the efficacy of changes in enhancement patte in assessing no-surgical treatment response in bronchogenic carcinoma preliminarily. Methods: Thirty-three patients with bronchogenic carcinoma underwent two-phase contrast material-enhanced computed tomography prior to and after stopping no-surgical treatment more than one-month respectively. Two spiral CT scans were obtained at 25 and 90 s respectively after nonionic contrast material was administrated via the antecubital vein at a rate of 3 mL/s by using an autoinjector. The sum of the tumor longest diameters (LD) prior to treatment, after treatment and the sum of the post-treatment tumor enhancement area LD on the images obtained at 90 s after injection of contrast medium were recorded. Precontrast and postcontrast attenuation on every scan was recorded and peak height was calculated. The significance of the difference among groups was analyzed by means of ANOVA, student t test and chi-square test. Results: The sum of the tumor LD prior to treatment, that of after treatment and the sum of the post-treatment tumor enhancement area LD on the images obtained at 90 s after injection of contrast medium were (4.49 ± 1.32), (4.05 ± 1.63), (3.36 ± 1.22) cm respectively and there were statistically significant differences mong them (f = 5.467, P = 0.006). The sum of the tumor LD prior to treatment was significantly higher than that of the post-treatment tumor enhancement area (P = 0.001). No statistically significant difference in the sum of the tumor LD was found between the pre- treatment and the post-treatment (P = 0.207). There was no statistically significant difference between the sum of the tumors LD and that of tumor enhancement area after treatment (P = 0.086). The response rate (RR) (21.21%)according to changes in sum of the tumor LD was significantly lower than that (30.30%) according to changes in the sum of the post-treatment tumor enhancement area LD (χ2 = 15.12, P < 0.05), and the progressive diseases (PD) rate (21.21%)was significantly higher than that (12.12%; χ2 = 14.12, P 0.05]. Peak height of bronchogenic carcinoma prior to treatment [(36.50 ± 11.21) HU] were significantly higher than that after treatment [(29.91 ± 10.35) HU; t = 10.081, P = 0.001]. Conclusion: Therapeutic effect may be underestimated with use of changes in sum of the tumor LD. The changes in sum of tumor enhancement area LD in addition to peak height is suggested to be used in assessing no-surgical treatment response in bronchogenic carcinoma.