Objective: To investigate possible relationship between the D-dimer and ischemia-modified albumin (IMA) levels and radiological imagingbased severity scores in pulmonary embolism (PE) based on two different radiological characteristics; the pulmonary arterial obstruction index (PAOI) and the right ventricle/left ventricle (RV/LV) ratio. Methods: In this prospective cohort study, forty-seven patients presenting to the emergency department and definitively diagnosed with PE using spiral computerized tomography (CT) were initially enrolled in the study. Levels of IMA and D-dimer were assessed colorimetrical and immuno-turbidimetric methods, respectively. The PAOI and RV/LV ratios were calculated from CT images. The levels of biochemical parameters between the groups were compared with use of Mann-Whitney U and Kruskal-Wallis tests and relationship between the radiological scores were assessed using the Spearman correlation test. Results: Analysis of the calculated PAOI and RV/LV ratio revealed a significant correlation between them (r=0.36, p=0.023). D-dimer levels differed considerably among the mild (<40%), moderate (40%-60%) and severe (60%) groups constituted on the basis of PAOI (p=0.039). This difference stemmed from those in D-dimer levels in the mild group, PAOI <40% and the severe group, PAOI 60% (p=0.02; Z= -2.328). In addition, D-dimer levels and PAOI revealed a positive correlation, but no similar correlation was determined between D-dimer levels and RV/LV. There were no significant correlations between IMA and D-dimer levels, PAOI and RV/LV ratios. Conclusion: In the biochemical determination of severity of PE based on radiological characteristics, D-dimer may be a more relevant marker than IMA, which has been proposed as a new marker. © 2010 by AVES Yayincilik Ltd.