Landfill leachates (LFL) constitute a serious environmental problem due to its high concentration of organic and inorganic compounds. However, landfill leachates can be also considered as fertilizer with respect to those substances. The present paper is an attempt to analyze the impact of application of municipal solid waste (MSW) landfill leachates on soil carbon, nitrogen and microbiological characteristics. Three doses of landfill leachates (0.5, 1 and 2%) were used corresponding to 10, 20 and 40 m3ha-1, respectively. The variation of the main physical, chemical and microbiological properties of soil was monitored. Temporary and permanent changes in several properties occurred after the application of LFL. These properties varied in sensitivity to the applied disturbance. Shortly, after the application of LFL the organic carbon and nitrogen (N) increased in soils amended. Simultaneously, an increase in the total number of soil bacteria, nitrifying populations and soil respiration (after two weeks of incubation) was occurred. But this effect disappeared after two months of treatment. The increase in microbiological activity accelerated the loss of soil organic carbon (SOC) and led to an increase of N at the end of incubation. The leachates treated soils exhibited elevated levels of electrical conductivity (EC) and lower levels of exchangeable Phosphorus (P).