Fatigue is a debilitating and common condition in cancer patients. This study examined pretreatment predictors of fatigue before chemotherapy and also assessed whether these could prospectively predict fatigue posttreatment. A total of 100 patients completed questionnaires assessing psychological factors, physical activity and sleep. A subsample of 26 participants wore actigraphs to objectively assess sleep/wake and activity/rest. Fatigue was measured pretreatment and posttreatment and at follow-up several months later. Greater pretreatment pain, depression, stress and sleep disruption significantly predicted greater fatigue before chemotherapy, explaining 55 percent of the variance. Pretreatment fatigue significantly predicted post-treatment fatigue. No other significant prospective predictors of posttreatment fatigue emerged.