In recent years, researchers have focused on acquiring a better understanding of the development of posttraumatic stress disorder (PTSD) in children under the age of six following exposure to chronic trauma, such as intimate partner violence (IPV). Despite a number of empirical studies on early childhood PTSD, few have examined how children differ in the clinical presentation of PTSD symptomatology. There may be wide variability in the presentation of symptoms within the four clusters of PTSD symptoms: re-experiencing, alterations in physiological arousal, negative alterations in cognitions and mood, and avoidance. Symptoms of physiological arousal may be particularly difficult for parents and therapists to identify and report on because many of these symptoms are internal sensations (e.g. racing heart beat), and they are most often evaluated out of context (e.g. in reports of past behaviour). Thus, little is known about the presentation of these symptoms in preschoolers. To better identify physiological arousal symptoms as they occur, this study examined therapists' qualitative reports on the presentation of physiological symptoms of 56 young children exposed to IPV while they participated in an intervention programme. Results indicated that children were most likely to exhibit emotion dysregulation, behavioural outbursts, mood swings and temper tantrums when physiologically aroused. The presence of temper tantrums as a component of arousal and reactivity is consistent with recent "Diagnostic and Statistical Manual of Mental Disorders" (fifth edition) changes, which include these elements as new criteria for PTSD in children aged six and younger. Behavioural examples are described and implications discussed for clinical intervention.