The purpose of this study is to determine the changes of leachate quality on a selected municipal landfill with recirculation of concentrate from the reverse osmosis process. The research was carried out on an exploited municipal waste landfill, from which in the years 2013-2015 samples of leachate, permeate and concentrate were collected. The obtained samples were subjected to physico-chemical analysis including the determination of general pollution parameters as well as organic and inorganic indicators. The obtained results have shown, that concentrate recirculation resulted in intensification of degradation processes in the waste body, expressed by the increase of biodegradability rate (BOD5/ COD) and the value of conductivity and dissolved solids. Over time, the value of conductivity and dissolved solids stabilized, reaching, however, values higher than in conventional landfills. A characteristic feature of long-recirculation landfills was a continuous increase in the concentration of ammonia nitrogen and COD values in the leachate.