Background: Financial relationships between physicians and the pharmaceutical industry are common, and have the potential to influence clinical practice in potentially inappropriate ways. Oncology may be an ideal setting to study the influence of industry payments on physician drug choice given the high levels of competition for market share and high prices commanded by orally administered oncologic drugs. Methods: We linked the Open Payments database of industry-physician financial transactions with the Medicare Part D Prescriber file by physician name and practice location. We used McFadden’s conditional logit model to determine whether receipt of industry payments was associated with higher odds of using a drug manufactured by the same company. We applied this model to clinical scenarios in which oncologists may choose between multiple, on-patent drugs: metastatic renal cell cancer (mRCC) (sunitinib, sorafenib, and pazopanib) and chronic myeloid leukemia (CML) (imatinib, dasatinib, and nilotinib). The primary, binary independent variable was receipt of payments from a manufacturer of one of these drugs in 2013; the primary dependent variable was choosing that manufacturer’s drug in 2014. We divided industry payments into two categories, research payments and non-research “general” payments (including meals, travel, lodging, and speaking/consulting fees), and analyzed each payment type separately. Results: Physicians who received general payments from a manufacturer had increased odds of prescribing that manufacturer’s drug for both mRCC (OR: 1.78, 95%CI 1.23-2.57, mean payments $566) and CML (OR: 1.29, 95%CI 1.13-1.48, mean payments $166). Research payments were associated with an increased odds of manufacturer drug use for mRCC (OR: 2.13, 95%CI 1.13-4.00, mean payments $33,391) but not CML (OR: 1.10, 95%CI 0.83-1.45, mean payments $185,763). Conclusions: Receipt of general payments from pharmaceutical companies is associated with increased prescribing of those companies’ drugs. An association between research payments and prescribing was less consistent. This study suggests that conflicts of interest with the pharmaceutical industry may influence oncologists in high-stakes treatment decisions for patients with cancer.