All patients with Parkinson's disease (PD) with motor fluctuations due to long-term levodopa therapy have at least one non-motor fluctuation symptom. Fluctuations of non-motor symptoms associated with levodopa action phases may influence patient's quality of life more negatively than motor fluctuations. However issues related to treatment of non-motor fluctuations have not been specially studied so far. We have carried out an open observational study of an effect of a combined formulation of levodopa, carbidopa and entacapone (stalevo) on non-motor fluctuations. Forty patients with PD were included in the study. A self-reported daily diary has been administered for assessment of motor and 12 most frequent non-motor symptoms (e.g., sweating, bladder dysfunction, short-breath, pain, fatigue, dysphoria, irritability). The principle of equivalence of levodopa daily dose was used while switching patients from a bicomponent levodopa formulation to stalevo. The condition of patients was evaluated at baseline and after 3 months of treatment. The duration of off-period has decreased on the average by 1,8 h a day. The reduction of autonomic and neuropsychiatric symptoms (sweating, heat and cold sensations, bladder dysfunction, short-breath, slowness of thinking) was found. The decrease in non-motor fluctuation severity was correlated with the reduction of off-period duration. Thus, stalevo exerts the effect both on motor fluctuations and on a wide range of fluctuating non-motor symptoms.