OBJECTIVES To describe the prevalence of Asthma, Diabetes Mellitus (DM) and Essential Hypertension (EH) in NAMCS 2006 and NHAMCS 2006, and determine the association between Health Insurance (HI) and Brand Status (BS) of prescribed diagnosis-specific medications. METHODS Inclusion criteria included patients with 1) physician diagnosis (in Dx1, Dx2 or Dx3) of asthma (ICD-9=493.0-493.9), DM (ICD-9=250.0-250.9) or EH (ICD-9=401.0-401.9); 2) matched respective chronic condition variables; and 3) at least one prescribed medication (Rx) for the medical condition. Patients with more than one chronic condition were excluded. Patients with private insurance, government insurance and no-insurance/uninsured were included in the study. Patients with blank, unknown or other HI categories were excluded. Rx was categorized into brand or generic. Chi-Square statistics were used to test the association between HI and BS. RESULTS In NAMCS 2006, a total of 656 (2.23%) out of 29,392 patients were included in the study. Of these, 206 (0.70%) patients had asthma, 94 (0.32%) had DM and 356 (1.21%) had EH. In NHAMCS 2006, out of 35,105 patients, a total of 910 (2.59%) were included in the study. Of these, 395 (1.12%) patients had asthma, 263 (0.75%) had DM and 252 (0.72%) had EH. Significant associations between HI and BS were discovered in patients with asthma (p=0.018) and EH (p=0.001) in NAMCS 2006. Private insurance patients with these medical conditions were more likely to be prescribed brand medications while patients with government or no-insurance were more likely to receive generic medications. No significant association was observed for DM in NAMCS 2006 and for all medical conditions in NHAMCS 2006 (p>0.05). CONCLUSIONS Health insurance appeared to have an influence on whether a patient with asthma or EH received brand or generic medications based on the data from NAMCS 2006. However, it seemed that the converse was true in NHAMCS 2006.