OBJECTIVES: COPD is the third leading cause of death with increasing mortality while other chronic condition mortality rates are decreasing.  This may be due to the fact that COPD is a complex chronic condition with a complicated diagnosis and treatment guideline in an aging patient population with increasing comorbid conditions.  The objective of this study was to understand the prevalence of comorbid conditions among COPD patients in the US.  METHODS: A retrospective database analysis was conducted using Marketscan Commercial and Medicare Supplement Data from year 1/1/2010 to 12/31/2011.  Patients were included if they had continuous medical and pharmacy benefits coverage for at least 12 months after their first COPD diagnosis defined as primary or ancillary ICD-9 codes of 491.xx, 492.xx, or 496.xx and were between the ages of 40 and 90 years old at the time of diagnosis. Univariate descriptive analyses were conducted to quantify comorbid disease prevalence.  RESULTS: Among the selected patients (n=231,827), 95.1% (n=220,519) had medical claims (ICD-9 codes) for diagnoses beyond COPD within 12 months of their COPD diagnosis.  The majority of patients were over 65 years old (61.4%, n=135,366).  Over 60% (n=130,325) of the patients had more than 3 comorbid conditions. The most common were hypertension (64.9%, n=143,189) (ICD-9 codes 401.xx-405.xx, 415, 416, 416.8, 459.1x and 459.3x), hyperlipidemia (46.5%,n=102,498) (ICD-9 code 272.x),  diabetes (27.8%, n=61,225) (ICD-9 code 249.xx, 250.xx, 253.5, 271.4, 357.2, 588.1, 790.29), coronary artery disease (27.4%, n=60,364) (ICD-9 code 414.0x, 414.3, 414.4), and asthma (22.7%, n=50,113) (ICD-9 code 493.xx).  CONCLUSIONS: Our results show the significant prevalence of comorbid conditions among COPD patients.  Further research on comorbid conditions impacting COPD patient treatment adherence, COPD pathogenic pathways and worsening overall prognosis are necessary.  More evidence is required to estimate the role of comorbidities in COPD.