Objective: To alert clinicians of the underreported complication of intraparenchymal lung hemorrhage during percutaneous radiofrequency ablation (RFA) of primary and secondary pulmonary malignancies. Methods: Of 101 RF ablations performed in 46 patients, 81 were retrospectively assessed for periprocedural intrapulmonary bleeding. The data was compared with the literature for this minimally invasive interventional treatment as well as with the reported frequency of lung hemorrhage during diagnostic lung biopsies. Results: Our incidence of hemorrhage during percutaneous lung RFA was 5.9%. The reported frequency in the scarce literature available is less than 1%. Data in the literature for percutaneous biopsy-related intraparenchymal hemorrhage ranges from 1.4% for fine-needle aspirations to 29% for core biopsies. Conclusion: Intraparenchymal lung hemorrhage during percutaneous RFA of primary and secondary pulmonary malignancies is similar to reported lung hemorrhage for diagnostic core biopsies. We believe this complication to be underreported in the literature.