OBJECTIVE To describe and compare the computed tomographic (CT) findings of pulmonary septic emboli in causative microorganisms. METHODS The CT findings of 16 patients (8 men and 8 women; age range, 17 to 80 years; mean, 53.1 years) with documented pulmonary septic emboli were retrospectively reviewed by 2 radiologists; their decisions on the findings were reached by consensus. Statistical analysis was performed using the t test and the chi test. RESULTS A total of 197 peripheral nodules were seen in 6 gram-positive (n = 88) and 10 gram-negative (n = 109) septic pulmonary emboli patients, respectively. The sizes of the nodules (15.94 mm; range, 3-46 mm) in gram-positive septic emboli were larger than those (12.29 mm; range, 4-44 mm) in gram-negative septic emboli (P = 0.006). Cavitation (n = 30 [34%] vs n = 23 [21%]; P = 0.041) and air bronchogram (n = 12 [14%] vs n = 4 [4%]; P = 0.008) within the nodules were more commonly seen in gram-positive septic emboli. A ground-glass attenuation halo around a nodule (n = 69 [63%] vs n = 32 [36%]; P = 0.000) and feeding vessel signs (n = 56 [51%] vs n = 25 [28%]; P = 0.001) were more commonly seen in gram-negative septic emboli. Wedge-shaped peripheral lesions abutting the pleura were seen in 4 gram-positive (67%) and in 1 gram-negative (10%) septic emboli patients, respectively (P = 0.047). CONCLUSIONS The detailed CT characteristics of peripheral nodules in pulmonary septic emboli may be able to differentiate the causative microorganisms and to provide additional information regarding treatment plans in patients with sepsis.