Objectives: To evaluate the agreements of unidimensional, bidimensional, area and volume measurements of pulmonary tumors on multidetector computed tomography (MDCT), and to determine which method is the most reliable one. Materials and methods: Thirty patients with pulmonary tumors were enrolled in this study, which referred to undergo thoracic MDCT in our hospital. Four radiologists evaluated dimensions of pulmonary tumor independently, including length, width, height, area and volume. The intraclass correlation coefficient (ICC) and concordance correlation coefficient (CCC) were both used to evaluate the variability between the repeat readings of the same scan. Results: The ICCs and CCCs of the intraobserver were both higher than interobserver's (ICC intra vs. inter: 0.984 vs. 0.947 and CCC intra vs. inter: 0.993 vs. 0.943). Area of intraobserver ICC (ICC=0.992, P<.001) and CCC (CCC=0.997, P<.001) both had the best agreements of the six methods. Among the interobserver ICCs and CCCs, area (ICC=0.981, P<.001 and CCC=0.982, P<.001) was also the best of the six methods. Conclusions: Area measurement on MDCT is the most reproducible method that measures tumor dimension accurately. (C) 2013 Published by Elsevier Inc.