We evaluated the efficacy and safety of alteplase to restore central venous line (CVL) patency in a consecutive cohort study. A uniform, weight-dependent protocol for alteplase administration was established prospectively. For children < or =10 kg, a dose of 0.5 mg was used; for children >10 kg, doses of 1 to 2 mg were used. The alteplase remained instilled for 1 to 4 hours or overnight. Retrospective data accrual found that 25 children received alteplase for a total of 34 courses; 29 (85%) of the 34 courses of alteplase completely restored CVL patency. Alteplase appears to be a safe and effective thrombolytic agent for CVL patency restoration in children.