Autologous HCT patients often have poor oral intake for 2-4 weeks post transplant. To compare outcomes between patients provided prophylactic total parenteral nutrition (TPN) or an oral diet (OD), 55 well nourished breast cancer/ hematopoietic cell transplantation (HCT) patients were randomized to TPN (n=27), beginning day -1, or OD (n=28). Parameters studied include length of stay (LOS), engraftment, infections, survival, weight, anthropometrics, handgrip strength, and quality of life (QOL) In all, 50% of OD patients were given TPN due to poor oral intake for 10 consecutive days. No significant differences were found between the groups for any of the above parameters except weight and anthropometrics, which were better maintained in the TPN group than the OD group. Trends were seen for increased infections, more stable handgrip strength, and improved QOL in the TPN group vs the OD group. Prophylactic TPN did result in a more intact nutritional status and preservation of lean body mass post transplant but did not impact LOS or survival when compared to OD. For this reason, TPN should be reserved for autologous HCT patients with pretransplant nutritional depletion, complications post transplant, or prolonged poor oral intake. These results should not be extrapolated to allogeneic HCT patients but are likely applicable to other well nourished autologous HCT patients.