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 posttreatment fatigue. No other significant prospective predictors of posttreatment fatigue emerged.