Objective: To evaluate if quality of care (QoC) provided by hospital is a determinant of ill-hospitalized adolescent's health-related quality of life (HRQoL) from parent's perspective. Design: Prospective cross-sectional study conducted at a tertiary care hospital of Northern India after institutional ethical approval. Setting: Hospital in pediatric department of a tertiary care, teaching medical University in Lucknow, northern India. Participants: Sick adolescents aged between 10 and 19 years and hospitalized for four categories of illnesses, namely, acute infective; chronic infective, non-hemopoetic; hemopoetic disorders and miscellaneous. Intervention: QOC assessment was done using 'Pyramid instrument' and HRQoL by culturally modified WHOQOL-BREF (World Health Organization Quality of Life-BREF). The Pyramid instrument comprises 43 questions to collect information about awareness of eight indices: namely illness, routines, accessibility, medical treatment, care processes, staff attitude, participation and staff work environment and scored on 1-4 Likert scale. WHOQOL-BREF has four domains: physical, psychological, social relations and environment and scored on 1-5 Likert scale. Results: From January 2008 to December 2008, 300 adolescents with a mean age of 12.5 ± 2.6 years and 61.3% males were included. The pyramid instrument showed a substantial internal consistency ($\alpha$ = 0.88, P-value < 0.0001). The mean QoC was highest for medical treatment (0.76 ± 0.13) and lowest for participation (0.54 ± 0.16). The mean parent's report of child's HRQoL was highest for physical (42.8 ± 7.4) and lowest for environment domain (37.2 ± 7.1). Four QoC indices namely, medical treatment, care processes, staff attitude and participation had significant associations with the mean HRQoL. In a hierarchical linear regression, staff attitude was the only significant determinant of HRQoL ($\beta$ coefficient: 23.16, 95% confidence interval: 15.8-30.5, P-value < 0.0001). Conclusion: The Pyramid instrument is a reliable instrument for assessing parent's perception of QoC provided to hospitalized adolescents in Indian context. QoC was positively associated with HRQoL, thus, an increased focus on QoC especially staff attitude is likely to enhance adolescent's overall HRQoL. {\textcopyright} The Author 2012. Published by Oxford University Press in association with the International Society for Quality in Health Care; all rights reserved.