OBJECTIVES: Estimate annual direct costs for privately-insured U.S. chronic thromboembolic pulmonary hypertension (CTEPH) patients and matched controls. METHODS: From a privately-insured claims database (>8 million beneficiaries, 2002-2007), 423 CTEPH patients were identified having: ≥2 claims for pulmonary hypertension (ICD-9: 416.0, 416.8); ≥1 claim for pulmonary embolism (ICD-9: 415.1, V12.51; ICD-9 procedure: 38.7; CPT-4: 36010, 37620, 75825, 75940; HCPCS: C1880) within 12 months prior or 1 month after the initial pulmonary hypertension claim (index date); ages 18-64.  Patients with CTEPH were matched demographically to controls without pulmonary hypertension.  All were required to have continuous coverage for 6 months before (baseline) and 1 month after index date.  A variable study period was used to follow patients as long as continuously eligible; mean follow-up was 20.5 months.   Chi-squared tests were used to compare baseline comorbidities.  Wilcoxon rank-sum tests were used for univariate comparisons of direct (medical and pharmaceutical) patient-month costs to insurers for CTEPH patients vs. controls. RESULTS: Average age for patients with CTEPH was 52.4 years, and 58.2% were women.  Compared with controls, CTEPH patients had significantly higher baseline rates of comorbidities (e.g., essential hypertension, congestive heart failure, chronic pulmonary disease, and diabetes) and a higher Charlson Comorbidity Index. Mean (median) direct patient-month costs were $4,456 ($1,305) for CTEPH patients and $457 ($90) for controls (p<0.0001), yielding excess costs of $3,999 ($1,215). Inpatient services accounted for 53%, outpatient services for 33%, and drug costs for 12% of CTEPH patient-month direct costs.  Circulatory/respiratory system-related patient-month costs were $2,289 ($617) among CTEPH patients and $110 ($7) among controls (p<0.0001), yielding excess costs of $2,179 ($610). CONCLUSIONS: Patients with CTEPH had substantially higher costs than matched controls.  Circulatory/respiratory system-related costs represented 51% of the costs of patients with CTEPH and 54% of the difference in costs between patients with CTEPH and controls.