The study assessed the quality of life of HIV/AIDS patients on Antiretroviral (ARV) Therapy and their caregivers at the National Hospital, Abuja. A sample of 200 participants comprising 150 patients and 50 caregivers was select for the study using the simple random sampling technique. The sample was drawn from the population of HIV/AIDS patients receiving ARV therapy from the Special Treatment Clinic (STC) at the National Hospital, Abuja. The sample of the caregivers was as well drawn from the same source. Three scales were adapted for use to collect data. They include: World Health Organisation Quality of Life bref, Zung Depression Guide Rating Scale and Zung Self-Rating Anxiety Scale. The instruments have a reliability coefficients of 0.78; 0.69, and 0.90 respectively. Also, a self-designed scale was used to measure the patients' drug adherence behaviour. Data generated were subjected to statistical manipulations using such tools as Analysis of Variance (ANOVA), t test, χ2, Pearson Product Moment Correlation and Multiple Regression Analysis. Also, scores of patients on the QOL scale were correlated with those of the caregivers. Seven hypotheses were tested for significance at 0.05 level and findings reveal that: though HIV/AIDS affects quality of life of AIDS patients, they are nonetheless able to live fulfilled lives and function normally when there is psychosocial support, enhanced social interaction and personal environmental health. Caregivers differ a great deal from patients in their quality of life, signifying the negative impact of the disease on the patients. Also revealed is that caregivers' quality of life does not significantly influence patients' quality of life (p value>0.05). Again, it was also discovered that patients' ARV therapy adherence behaviour does not significantly impact on quality of life (p value>0.05). Other factors were therefore suspected to be contributing more to QOL of patients than mere therapy adherence. Patients' social demographic characteristics jointly contribute to quality of life. And when isolated, patients' job status and their religious belief/affiliations impact significantly on QOL. The mean scores of patients on the four domains of QOL were compared. Patients' performance was highest in the environmental health domain, followed by that of social relationship domain and then, the psychological health domain. Physical health domain had the least mean score. Meanwhile, scores of the four domains of quality of life jointly impact significantly to the overall quality of life of patients. Further, scores on depression and anxiety were compared with those of QOL and result showed that both depression and anxiety reduce patients' quality of life with depression making the strongest negative impact on quality of life. However, gender, age and marital status do not make any significant difference in quality of life among patients. Implications of these findings were further discussed and effective measures for improving quality of life of patients of HIV/AIDS were recommended.