Hydrochemical research conducted in the years 2007–2010 comprised monitoring of the Włosanka stream waters and leachate waters from the municipal landfill in Kulerzów in the Malopolskie province. 16 leachate samples were collected from the container taking into consideration the vertical stratification of the quality and samples of water from the Włosanka stream in measurement points situated before and after the landfill. Concentrations of metals: calcium, magnesium, sodium, potassium, iron, manganese and heavy metals: chromium, zinc, copper, cadmium, nickel and lead were determined in the leachates and the stream water. Analysis of the studied metals in the leachates revealed that only potassium concentration exceeded the highest admissible value which is the condition of introducing sewage to water bodies or to soil. Water along the investigated reach of the Włosanka stream, both above and below the municipal landfill was of quality class 1. The landfill had no significant effect on the studied metal concentrations in the stream water – no statistically significant differences were registered between the concentrations of the studied metals (including heavy metals) either in the point above or below the landfill. However, statistical tests comparing values of metal concentrations in the landfill leachates with the stream water revealed that the concentrations of 7 out of 12 tested metals were significantly higher in the leachates. Therefore, the landfill site monitoring should be continued, leachate waters should be collected in the container and supplied to the sewage treatment plant to prevent any threat to human life and health, or to the environment.