The objective of the analysis was the quality of electric energy in the place of attachment of a single wind power plant to the electricity grid. This objective was performed based on the author's own research carried out in a LV switching station located in the place of attachment of a wind turbine with the power 150 kW to the MV distribution network. The object of the research was located in the northern part of Małopolskie Voivodeship. The assessment of the quality of electric energy was carried out based on the requirements set forth in the Ordinance of the Minister of Economy on detailed conditions of functioning of the power system and the Manual of Movement and Operation of Distributive Network. Based on the analysis, which was carried out, one may assume that the requirements referring to frequency changes, efficient value of the supply voltage, voltage unbalance and its deformation from the sinusoidal waveform have been met. In the period which was covered by the research, during the wind turbine work, insignificant surpasses of the admissible level of the root mean square of voltage were reported, but their number constituted less than 0.07% of observations. During the research, also 20 voltage dips of values exceeding 10% of the rated voltage, average depth of which was 172V were reported. In majority these were disruptions caused by other receivers connected to the network.