In patients with traumatic brain injury (TBI), intracranial hypertension secondary to cerebral edema is a major problem. A last-tier treatment in these cases is decompressive craniectomy. The aim of the present retrospective investigation was to (1) study the long-time outcome in patients with traumatic head injuries with intracranial hypertension treated with decompressive craniectomy; (2) examine the effects on intracranial pressure (ICP) by the craniectomy; and (3) investigate the possible relationship between the size of the removed bone-flap and the effects on ICP. Among the about 150 patients with severe TBI treated at our neurointensive care unit during 1997-2002, 19 patients were treated with decompressive craniectomy. All patients were young (mean 22 +/- 11 years, range 7-46 years), and 68% were male. The mean ICP was reduced from 29.2 +/- 3.5 before to 11.1 +/- 6.0 mm Hg immediately after the craniectomy; at 24 h after the craniectomy, the mean ICP was 13.9 +/- 9.7 mm Hg. Paired-samples t-test revealed a statistically significant decrease, both when comparing the preoperative values to the values immediately postoperative as well as to the values after 24 h (p < 0.01). A significant correlation between the size of the craniectomy and the decrease in ICP was found using Pearson regression analysis. The outcome of all patients could be assessed. The survival rate was 89%. Two patients died (both day 4 after the trauma); 68% of the patients had a favorable outcome (Glasgow Outcome Scale [GOS] score of 4 or 5); 16% were severely disabled (GOS score of 3); and one patient (5%) was left in a vegetative state.