AIMS: We evaluated pedometry as a novel patient-centered outcome because it enables passive continuous assessment of activity and may provide information about the consequences of symptomatic toxicity complementary to self-report. METHODS: Adult patients undergoing hematopoietic cell transplant (HCT) wore pedometers and completed PRO assessments during transplant hospitalization (4 weeks) and 4 weeks post-discharge. Patient reports of symptomatic treatment toxicities (single items from PRO-CTCAE, http://healthcaredelivery.cancer.gov/pro-ctcae ) and symptoms, physical health, mental health, and quality of life (PROMIS(®) Global-10, http://nih.promis.org ), assessed weekly with 7-day recall on Likert scales, were compared individually with pedometry data, summarized as average daily steps per week, using linear mixed models. RESULTS: Thirty-two patients [mean age 55 (SD = 14), 63 % male, 84 % white, 56 % autologous, 43 % allogeneic] completed a mean 4.6 (SD = 1.5, range 1-8) evaluable assessments. Regression model coefficients (β) indicated within-person decrements in average daily steps were associated with increases in pain (β = -852; 852 fewer steps per unit increase in pain score, p < 0.001), fatigue (β = -886, p < 0.001), vomiting (β = -518, p < 0.01), shaking/chills (β = -587, p < 0.01), diarrhea (β = -719, p < 0.001), shortness of breath (β = -1018, p < 0.05), reduction in carrying out social activities (β = 705, p < 0.01) or physical activities (β = 618, p < 0.01), and global physical health (β = 101, p < 0.001), but not global mental health or quality of life. CONCLUSIONS: In this small sample of HCT recipients, more severe symptoms, impaired physical health, and restrictions in the performance of usual daily activities were associated with statistically significant decrements in objectively measured daily steps. Pedometry may be a valuable outcome measure and validation anchor in clinical research.