Animal models are very popular in medicine, including psychiatry, having the potential to provide a better understanding of various facets of the course, etiology and treatment of disorders. One of the disorders authors have been focusing their attention on is posttraumatic stress disorder (PTSD). In order to provide appropriate information about the disorder the model has to meet several criteria. It has been postulated that even very brief stressors should be capable of inducing biological and behavioural symptoms of PTSD, that the stressor should be capable of inducing the symptoms in a dose-dependent manner, that the symptoms should persist over time or even become more pronounced, that the stressor should induce alterations that have the potential for bi-directional expression; enhanced (hyperarousal) and reduced (avoidance and/or numbing) responsiveness to environmental stimuli which recall the initial trauma and that interindividual variability in response to a stressor should be present either as a function of experience, genetics, or an interaction of the two. Researchers use a variety of stressors to induce PTSD-like symptoms in animals most of which are uncontrollable and unescapable. Both human and animal reactions to threats bear a high degree of similarity. The symptoms observed in animals exposed to a threatening situation resemble those observed in PTSD patients and include behavioural and physiological stress symptoms, avoidance of stimuli associated with an aversive experience, analgesia, disrupted sleep patterns, increased aggressive behaviour, hyperarousal and exaggerated startle response. In the article a number of models of PTSD are being evaluated as to whether they meet the criteria of an ideal model. The criterion most rarely met is taking into account individual differences in the vulnerability to PTSD.