The intranuclear cascade model (INC) was was first proposed by Serber in 1947 . He noticed that in particle-nuclear collisions the deBroglie wavelength of the incident particle is comparable (or shorter) than the average intra-nucleon distance. Hence, a description of interactions in terms of particle-particle collisions is justified.
The INC has been used succesfully in Monte Carlo simulations at intermediate energies since Goldberger made the first hand-calculations in 1947 . The first computer simulations were done by Metropolis et al. in 1958 . Standard methods in INC implementations were developed when Bertini published his results in 1968 . An important addition to INC was the exciton model introduced by Griffin in 1966 .
The current presentation describes the implementation of the Bertini INC model within the GEANT4 hadronic physics framework . This framework is flexible and allows for the modular implementation of various kinds of hadronic interactions. It is based on the concepts of physics processes and models. While the process is a general concept, models may be restricted according to process type, material, element and energy range. Several models can be utilized by one process class; for instance, a process class for inelastic collisions can use a different model for each energy range.
The process classes use model classes to determine the secondaries produced in the interaction and to calculate the momenta of the particles. Here we present a collection of such models which describe a medium-energy intranuclear cascade.