This report presents a dynamical model for the fate of Bacillus cereus in the gastro-intestinal tract. Biological processes and system dynamics are simultaneously incorporated in this mechanistic model. Variability in growth characteristics and physical traits of different B. cereus strains are expressed through the incorporation of a range of reasonable parameter values obtained from experiments. Different hypothesis concerning initial ingestion of B. cereus microbes and following in vivo processes leading to a potential infection are tested. Model outputs show the course of (attached) vegetative cells and/or spores in the stomach and small intestine during the digestion of B. cereus microbes. Results give insight in biophysical conditions under which B. cereus can form an increased hazard for food intoxication. This model shows that a potential increased food intoxication hazard results from the consumption of food containing, at least, slightly mesophilic B. cereus strains. Furthermore, this model gives insight in which mechanisms need elaborated investigation to come to an improved model and, with that, to improved suggestions for food microbiological criteria.