INTRODUCTION We aimed to examine the relative importance of medical and psychosocial needs of Asian breast cancer patients and their caregivers, and to identify the determinants of quality of life (QoL) at the time of diagnosis. METHODS This is a prospective observational study of the perceived needs and QoL of 99 dyads of breast cancer patients and their caregivers at diagnosis. A self-administered questionnaire was used to measure the perceived importance of medical and psychosocial support needs. Short Form-36 health survey (SF-36) version 2 was used to measure QoL. We also collected patient and caregiver demographic profiles and disease-specific information. Descriptive analysis of perceived needs was performed. SF-36 scores for eight domains and composite scores were calculated. Bivariate analysis and linear regression were performed to identify significant independent predictors of QoL of patients and caregivers. RESULTS The mean ages of the patients and caregivers were 56.5 years and 51.7 years, respectively. To have family around (73%), prompt information about treatment and treatment options, including side effects (71%), and prompt treatment for side effects (71%) were the top three needs among patients and their caregivers. Supportive nurses and prompt treatment for side effects positively improved patients' social functioning and bodily pain scores. Stage of disease, age, education and ethnicity also influenced QoL. Only the presence of chronic disease influenced caregivers' physical functioning and role-physical scores. CONCLUSION Patients and caregivers have similar perceptions of needs at diagnosis. A supportive healthcare team can positively influence patients' QoL, highlighting the importance of tailoring support according to needs.