The software tool HIPPO allows biologists to produce models that are realistic biologically without having to write complex computer programs. Specification of models is simplified by using a graphical user interface and distribution of models to both scientific and commercial users is expedited by generating platform independent C code that can be linked to a variety of interfaces. Individual based and life cycle models, which are relevant to many biological problems, are easily represented. Some relevant features of HIPPO are described and an example of a prey-predator-plant interaction is demonstrated.