The aim of this retrospective study was to ascertain whether physiological derangement and potential secondary brain insult from raised intracranial pressure (ICP) or reduced cerebral perfusion pressure (CPP) in non-accidental head injury (NAHI) influences outcome. Any child who had a diagnosis of NAHI and had ICP monitoring or measurements during the acute illness was entered in the study. Seventeen children with an average age 5.1 months (range 1 to 20 months) were identified. Details of the acute encephalopathy, lowest mean arterial blood pressure (MAP), mean of maximum ICP measured, lowest CPP, and neurodevelopmental outcome at follow up were obtained from the hospital case notes. Seshia's (1994) outcome classification scale was used. The lowest CPP was very significantly related to outcome (P=0.0047, tau=-0.544). Mean of maximum ICP did not correlate with outcome. The lowest MAP was significantly related to outcome (P=0.039). It was concluded that the degree of secondary brain insult from reduced CPP influences outcome.