Studies were carried out in the years 2008-2010 in Lake Starzyc, zachodniopomorskie voivodship. The aim was to determine differences in the concentrations of selected water quality parameters between particular months of the vegetation seasons 2008-2010. Monthly mean concentrations of dissolved oxygen between April and October were by 1.91 g O2m-3 higher in surface than in near-bottom water layer. Differences in the concentration of dissolved oxygen were also noted between particular months. Recorded concentrations fell within the range required for lake waters of the first and second water quality. Concentrations of mineral nitrogen in the years 2008-2010 corresponded to those of the third class of water quality and phosphorus concentrations exceeded this standard. Concentrations of ammonium ions did not exceed the values permitted for the second water quality class.