Background: National and International Hematology/Oncology Practice guidelines recommend testing for the BCR-ABL mutation for definitive diagnosis of chronic myeloid leukemia (CML) to allow for appropriate treatment with a Tyrosine Kinase Inhibitor (TKI). The purpose of our study is to describe population-based testing and treatment practice characteristics for patients diagnosed with CML. Methods: We analyzed cases of CML using 2011 data from the Centers for Disease Control and Prevention’s (CDC) Comparative Effectiveness Research (CER) Project collected by 10 specialized state central cancer registries in the US. We described completeness of testing for the BCR-ABL gene mutation and availability of outpatient treatment with TKIs and associated characteristics. Results: A total of 717 cases of CML were identified; 380 (53%) had a documented BCR-ABL gene test with 365 (51%) documented as BCR-ABL positive. Another 15 (2%) patients had BCR-ABL gene testing completed but were either negative or had a missing result. Of cases tested for the BCR-ABL gene, TKIs were recorded in 303 (80%) of these cases. One state registry reported a significantly higher percentage of incomplete BCR-ABL gene testing (p < 0.001) and TKI treatment (p < 0.001). Limiting analysis to CML cases reported from the remaining nine specialized registries, 307 (79%) had a documented BCR-ABL gene test; 271 (88%) of those tested had documented treatment with a TKI. Receipt of testing or treatment for these nine states did not vary by sex, race, ethnicity, poverty level, rural/urban residence, or insurance status; BCR-ABL testing was performed less often with increasing age as was treatment with TKIs (p = 0.0001, p = 0.007 respectively). Conclusions: Collection of detailed CML data can vary significantly by states. A majority of the case patients had appropriate testing for the BCR-ABL gene and treatment with tyrosine kinase inhibitors. However, BCRABL testing and TKI treatment decreased with increasing age. Further research is needed to understand CML testing and treatment disparities.