ABSTRACT: During hospitalization for hematopoietic stem cell transplantation (HCT), patients receive high-dose chemotherapy before transplantation and experience significant physical and psychological symptoms and poor quality of life (QOL).To assess the effect of inpatient palliative care on patient- and caregiver-reported outcomes during hospitalization for HCT and 3 months after transplantation.Nonblinded randomized clinical trial among 160 adults with hematologic malignancies undergoing autologous/allogeneic HCT and their caregivers (n?=?94). The study was conducted from August 2014 to January 2016 in a Boston hospital; follow-up was completed in May 2016.Patients assigned to the intervention (n=81) were seen by palliative care clinicians at least twice a week during HCT hospitalization; the palliative intervention was focused on management of physical and psychological symptoms. Patients assigned to standard transplant care (n=79) could be seen by palliative care clinicians on request.Primary: change in patient QOL from baseline to week 2; secondary: patient-assessed mood, fatigue, and symptom burden scores at baseline, 2 weeks, and 3 months after HCT and caregiver-assessed QOL and mood at baseline and 2 weeks after HCT.Among 160 enrolled patients (mean age, 60 [SD, 13.3] years; 91 women [56.9%]; median hospital stay, 21 days) and 94 caregivers, 157 (98.1%) and 89 (94.7%), respectively, completed 2-week follow-up, and 149 patients (93.1%) completed 3-month follow-up. Patients in the intervention group reported a smaller decrease in QOL from baseline to week 2 (mean baseline score, 110.26; week 2 score, 95.46; mean change, -14.72) compared with patients in the control group (mean baseline score, 106.83; week 2 score, 85.42; mean change, -21.54; difference between groups, -6.82; 95% CI, -13.48 to -0.16; P?=?.045). Among the secondary outcomes, from baseline to week 2, patients in the intervention group vs those in the control group had less increase in depression (mean, 2.43 vs 3.94; mean difference, 1.52; 95% CI, 0.23-2.81; P?=?.02), lower anxiety (mean, -0.80 vs 1.12; mean difference, 1.92; 95% CI, 0.83-3.01; P?