BACKGROUND: Intracranial hypertension (ICH) and hyperthermia are common after traumatic brain injury (TBI) and associated with worse neurological outcomes. This study sets out to determine the combined power of temperature and intracranial pressure (ICP) for predicting neurologic outcomes and prolonged length of stay (LOS) following severe TBI. METHODS: High resolution (every 6 seconds) temperature and ICP data were collected in adults with severe TBI from 2008-2010. Temperatures were plotted against concurrent ICP and divided based on breakpoints (Temperature: <36, 36-38.5 or >38.5 °C, ICP: <20, 20-30 or >30 mmHg). The percentage of time spent in each section, as well as several pooled unfavourable conditions (hyperthermia ± ICH), were then evaluated for predictive value for ICU-LOS > 7 days and short-term (<6 months) vs. long-term (>6 months) dichotomized neurologic outcomes. RESULTS: Fifty patients were included for analysis with severe TBI. Evaluation of the area under the operating receiver curve (AUC) showed significant periods of fever and high ICP (<30 mmHg) had a strong association with poor long-term neurological outcomes (Day 3, AUC = 0.71, p = 0.04) and were higher than either condition alone. ICU-LOS > 7 days was increased when hyperthermia and/or ICH remained uncontrolled by Day 5 (AUC = 0.82, p = 0.02). SUMMARY: Hyperthermia combined with ICH were shown to be significant prognostic indicators of future poor neurologic outcomes in patients with severe traumatic brain injury.