Cancer-related fatigue is the most prevalent and distressing symptom experienced by patients with advanced cancer. Central nervous system stimulants have been shown to relieve fatigue in nonmalignant disease. Modafinil is a stimulant with a selective site of action in the brain that is better tolerated than traditional stimulants, such as methylphenidate. The aim of this study was to determine the feasibility of conducting a randomised controlled trial to assess the efficacy and safety of modafinil for the treatment of fatigue in patients with lung cancer. Twenty patients with non-small cell lung cancer were recruited to this open-label study. Modafinil was taken in a fixed dose-titration schedule of 100 mg daily for 7 days followed by 200 mg daily for 7 days. Fifteen patients completed the study. During the study period, there was a rapid and statistically significant reduction in the primary outcome, fatigue (P = 0.001) and the secondary outcomes of daytime sleepiness and depression/anxiety. This improvement in fatigue was also clinically significant. Ten patients chose to continue modafinil after the study and the drug was well-tolerated. It would be both feasible and worthwhile to conduct a definitive randomised controlled trial to determine the role of modafinil in the treatment of cancer-related fatigue.