Disorders of initiation and maintenance of sleep (DIMS), excessive daytime sleepiness (EDS) are common and clinically significant in patients with Parkinson's disease (PD). The aim of the study was the evaluation of the effects of the dopamine agonist pramipexole on DIMS and EDS in PD. Sixty-seven patients with PD (mean age 63,2±9,9 years old, mean illness duration 6,5±4,2 years) were enrolled in the study. Forty patients received pramipexole as add-on to the other antiparkinsonian medications in mean daily dosage 2,64±0,6 mg. Clinical symptoms were assessed using the UPDRS, the PDSS, the PSO, the ESS, the Beck Depression Inventory (BDI), the Spielberger's State Anxiety Inventory, the SCOPA-Cog, the PDQ-39. The most common sleep complaints were sleep fragmentation and early awakening. DIMS, EDS were the main factors which negatively influenced the overall quality of sleep. The administration of pramipexole significantly improved the overall quality of sleep, decreased sleep initiation difficulties and sleep fragmentation, night and early morning dystonia, early morning tremor; restlessness, troublesome sensations in extremities, nocturia. We speculate that the effects of therapy on DIMS are caused by the decrease of nocturnal PD motor (hypokinesia, dystonia, tremor) and nonmotor (nocturia, sensor disturbances) symptoms; 15% of patients had moderate ESS in the early treatment period.