To study the factors associated with poorer health-related quality of life at 1-year post-allogeneic hematopoietic cell transplantation (alloHCT), a secondary analysis of a prospective feasibility study was performed. Pediatric Quality of Life Inventory questionnaires were collected in 76 children undergoing alloHCT at baseline (within 30 d before transplantation), day 100, 6 months, and 12 months posttransplantation. The global score improved post-HCT (baseline: 67.1, 12 mo: 76.6). Females (odds ratio, 6.5; 95% confidence interval, 1.002-42.17; P=0.04) and patients with low baseline scores (odds ratio, 7.2; 95% confidence interval, 1.07-48.63; P=0.04) had lower scores at 12 months post-HCT and suggest a target group for early interventions such as physical exercise, stress management, and cognitive behavior therapy.