The exponential growth in medical pharmaceuticals and related clinical trials have created a need to better understand the decision-making factors in the processes for developing hospital medication formularies. The purpose of the study was to identify, rank, and compare major factors impacting hospital formulary decision-making among three prescriber groups serving on a hospital's pharmacy and therapeutics (P&T) committee. Prescribers were selected from the University of Texas, MD Anderson Cancer Center which is a large, multi-facility, academic oncology hospital. Specifically, the prescriber groups studied were comprised of physicians, midlevel providers, and pharmacists. A self-administered online survey was disseminated to participants. Seven major hospital formulary decision-making factors were identified in the scientific literature. Study participants were asked to respond to questions about each of the hospital formulary decision-making factors and to rank the various formulary decision-making factors from the factor deemed most important to the factor deemed least important. There are five major conclusions drawn from the study including three similarities and two significant differences among the prescriber groups and factors. Similarities include: (1) the factor "pharmacy staff's evaluation of medical evidence including formulary recommendations" was ranked highest for all three prescriber groups; (2) "evaluation of medications by expert physicians" was ranked second for physicians and midlevel providers while pharmacists ranked it third; and (3) the factor, "financial impact of the treatment to the patient" was fifth in terms of hospital formulary decision-making statement and ranking by all three prescriber groups. Two significant differences include: (1) for the hospital-formulary decision making statement, "I consider the number of patients affected by adding, removing, or modifying a drug on the formulary when making hospital medication formulary decisions," midlevel providers considered this factor of significantly greater importance than did physicians; and (2) for the ranked hospital formulary decision-making factor, "financial impact of treatment to the institution," pharmacists ranked this factor significantly higher than did physicians. This study contributes to a greater understanding of the three prescriber groups serving on a P&T committee. Also, the study contributes to the body of literature regarding decision-making processes in medicine and specifically factors impacting hospital formulary decision-making. Furthermore, this study has the potential to impact the operational guidelines for the P&T committee at the University of Texas, MD Anderson Cancer Center as well as other hospitals.