Background: A subset of children with cITP is at increased risk for severe bleeding and functional limitations. We evaluated the HRQL of children with cITP as part of a multicenter, open label Phase I/II clinical trial of four weekly doses of Rituximab, evaluated for response at 12 weeks. Responders had a ≥ 50,000/mm3 platelet count over weeks 9–12 without other supportive therapy. Methods: All participating parents were invited to complete the Child Health Ratings Inventories (CHRIs) at baseline and 12 wks. The CHRIs, a generic HRQL questionnaire, contains 20 items, forming four domains in the areas of physical, role, and emotional functioning, and school. Each item has a five-point Likert response scale. Domain scores range from 0–100, with higher scores connoting better functioning. Of the 36 study participants, 24 parents opted to participate in the HRQL evaluation; 22 of 24 (91%) completed both the baseline and 12-week assessments. The baseline clinical profile and 12-week Rituximab response rates of HRQL participants and non participants (n=12) were compared. Potential clinical covariates (e.g., duration of illness, worst bleeding score, platelet count, number of prior therapies) were examined in a univariate analysis (UVA) with baseline HRQL domain scores. Regression analyses (MVA) adjusting for age and gender were used to assess the effects of treatment response and clinical covariates on the mean change in scores between baseline and week 12. Results: While HRQL participants had more previous treatments and lower platelet counts than nonparticipants, their clinical profile was otherwise similar; Rituximab response rates did not differ. Mean HRQL domain scores (standard deviation) at baseline were as follows: physical-52.1 (36.2); role-78.6 (23.7); emotional-63.4 (18.3); school-64.1 (25.8). Lower platelet count and greater number of prior therapies were significantly associated with worse baseline HRQL scores on UVA. By week 12, 36% (8/22) responded to Rituximab. Clinically meaningful improvements in HRQL scores (≥ 0.5 standard deviation improvement) were observed in responders; no change was detected in non-responders. In MVA, responder status contributed the predominate effect on the HRQL change scores, with the greatest improvement noted in emotional functioning (p=.002). No other clinical variables emerged in this limited sample size. Conclusions: The pattern of parent-reported HRQL scores for these children with severe cITP mirrored scores from other severe, pediatric health conditions. Significant improvements in HRQL were observed among Rituximab responders over the 12-week period while non-responders had no change. Further overall characterization of HRQL in the cITP pediatric population is needed.