Much recent literature supports the resurgence of the intraosseous route of access in pediatrics. Intraosseous lines provide a timely noncollapsable route to the circulation in medical or traumatic emergencies when intravenous access is not possible. There has been no controlled study comparing intravenous and intraosseous loading of phenytoin. A 15 mg/kg dose of phenytoin was administered over 15 minutes to pigs by either the intravenous (n = 6) or tibial intraosseous route (n = 6). Femoral artery blood samples were drawn every 5 minutes for 35 minutes after initiation of infusion to determine phenytoin levels. There was no statistical difference between the two groups using analysis of variance repeated measures (P = .160). Microscopic examination of the cortex and marrow at the intraosseous site in these pigs was normal 5 weeks postinfusion. The authors conclude that the intraosseous route is an effective alternative to intravenous loading of phenytoin without permanent damage to the marrow.