Chronic fatigue syndrome (CFS), a specific asthenic condition, is identified in a half of patients with Parkinson's disease (PD). An aim of the study was to evaluate an effect of melatonin (melaxen) on the severity of CFS, affective disorders, quality of life and sleep disorders in 30 patients with early and late stages of PD. After treatment, there was a decrease by 21% (p<0,05) on the Parkinson fatigue scale. At the same time, the improvement of sleep, assessed by the PDSS, decrease in the state anxiety on the Spilberger's scale and improvement of quality of life on the PDQ-39 (p<0,05) were found. No significant differences in motor, cognitive autonomic disorders and depression level were noted compared to baseline. Therefore, melatonin, together with optimized antiparkinsonian treatment, can treat CFS, improve sleep and quality of life of PD patients.