Background: No prior study to our knowledge has observed the cost of managing solitary, pulmonary nodules of patient groups defined by PET scan results. Methods: We combined study and administrative data over 2 years of follow-up. Results: Of 375 individuals with a definitive diagnosis, 54.4% had a malignant nodule and 62.1% had positive PET scan results. Mortality risk was 5.0 times higher (CI, 3.1-8.2) and cost was greater ($50,233 vs $22,461, P < .0001.) among patients with malignant nodule. Mortality risk was 4.1 times higher (CI, 2.4-7.0) and cost was greater ($47,823 vs $20,744, P < .0001) among patients with a positive PET scan result. Among patients with a malignant nodule, 4.9% had a false-negative PET scan, but cost and survival were not different from true positives. Among patients with a benign nodule, 22.8% had a false-positive PET scan. These patients had greater cost ($33,783 vs $19,115, P < .01), more: surgeries and biopsies, and 3.8 times the mortality risk (CI, 1.6-9.2) of true negatives. Just over one-half (54.5%) of individuals with positive PET scans received surgery. Most individuals with negative PET scans (85.2%) were managed by watchful waiting. They incurred fewer costs than patients with negative PET scans who were managed more aggressively, ($19,378 vs $28,611, P < .01). Conclusions: Management of solitary, pulmonary nodules is expensive, especially if the nodule is malignant or if the PET scan result is false positive. Among patients with malignant nodules, 2-year survival is poor. Compared with true-positive PET scan results, false-negative results are not associated with lower costs or better outcomes. CHEST 2010; 137(1):53-59