Currently, waste generation in Indonesia is increasing; the amount of waste generated in a year is around 67.8 million tons. Increasing the amount of waste generation can cause other problems, namely water from the decay of waste called leachate. Leachate can contaminate surface water, groundwater, or soil if it is streamed directly into the environment without treatment. Between physical and chemical, biological methods, and leachate transfer, the most effective treatment is the biological method. The purpose of this article is to understand the biological method for leachate treatment in landfills. It can be concluded that each method has different treatment results because it depends on the leachate characteristics and the treatment method. These biological methods used to treat leachate, even with various leachate characteristics, also can be combined to produce effluent from leachate treatment below the established standards.