Existing predictive landfill model vary in their model complexity, predictive capability, accuracy, extent of landfill components that they cover and the required number of parameters needed to run the model. The landfill components that the more complex models include are: Biological/Microbial processes; Biochemical processes; Transport of liquid, gases and heat. Whereas the simpler models only simulate the microbial growth and decay and ignore the other processes which occur in a landfill. They also assume that the wastes are placed instantaneously and the landfill is homogenous. This abstract discusses the data requirements for the different model types.