Quality of life (QoL) is a multi-dimensional phenomenon bordering on all aspects of one’s life. The aim of this study was to determine the factors that are considered predictors of QoL in a Lebanese sample of cancer patients attending a tertiary healthcare center. A cross-sectional descriptive survey was used. A total of 200 adult oncology patients over 18 years of age were interviewed over a one-year period, 2009-2010. Two widely known instruments were used; the European Organization for Research and Treatment of Cancer-Quality of Life Questionnaire (EORTC QLQ-C30) and the Memorial Symptom Assessment Scale (MSAS) to evaluate the QoL and symptoms experienced in this population group. The reliability coefficients of both instruments were generally satisfactory. The results showed significant predictors of better QoL were being married (p = 0.04) and being single (p = 0.04), having breast (p = 0.01) and gastro-intestinal cancer (0.02) as primary cancer sites and emotional functioning (p = 0.00); significant predictors of poorer QoL were the MSAS total symptoms (p = 0.01) and fatigue (p = 0.00). Our findings provide insight into the predictors of QoL of cancer patients and set the path for future research in order to improve the QoL of cancer patients in Lebanon.