The results of a survey to characterize oncology drug shortages across the United States and the impact of shortages on clinical practice, patient safety, clinical trials, and health care costs are presented. A 34-item online survey was distributed to 1672 members of the Hematology/Oncology Pharmacy Association and other organizations to gather information on shortages of oncology drugs (i.e., all drugs essential in the care of cancer patients, including supportive care agents). Two hundred forty-three completed responses, almost all from pharmacists (97%), were analyzed. Delays in chemotherapy administration or changes in treatment regimens due to drug shortages were reported by 93% of survey participants; 85% of respondents reported increased costs, and 10% reported reimbursement challenges related to drug shortages. At 34% of represented institutions, at least 1000 hours of additional labor annually was needed to manage shortages. Changes in therapy leading to near-miss errors were reported by 16% of participants, with 6% reporting one or more actual medication errors attributable to a drug shortage. The oncology medications most frequently reported to be in short supply during the preceding 12 months were fluorouracil, leucovorin, liposomal doxorubicin, and paclitaxel. The conduct of clinical trials was affected by drug shortages at 44% of represented institutions. A survey of U.S. oncology pharmacists indicated that oncology drug shortages occurred frequently in the first half of 2011. Shortages led to delays in chemotherapy and changes in therapy, complicated the conduct of clinical research, increased the risks of medication errors and adverse outcomes, and increased medication costs.