We treated percutaneously 135 expanded polytetrafluoroethylene (PTFE) prosthetic grafts which had thrombosed using thrombolysis with urokinase followed by balloon angioplasty. Functional patency was re-established in 38 of 62 (61%) using single catheter technique, and in 62 of 73 (85%) using crossed catheter technique (P < 0.01). Hemorrhagic complications were reduced from 12.9% in the single catheter technique to 1.4% in the crossed catheter technique (P < 0.01). Median "primary patency after treatment" of the PTFE accesses after successful restoration of function was 98 days. Cumulative "primary patency after treatment" from the time of successful recanalization of the thrombosis for the PTFE grafts was 70.5% at one month, 45.8% at 6 months, and 16.2% at 12 months. Among a smaller group of 26 PTFE patients who were treated with only interventional radiologic procedures (repeat thrombolysis and/or angioplasty), without surgical revision, "secondary patency after treatment" from the time of thrombosis was 92.3% at 1 month, 80.2% at 6 months, 69.4% at 12 months, and 36.5% at 24 months. We conclude that lysis/angioplasty is a valuable means of treating thrombosed hemodialysis access sites. The crossed catheter technique produces superior initial technical success compared with single catheter infusion of the lytic agent. "Primary patency after treatment" after successful recanalization is relatively short, but long-term patency is improved substantially with retreatment of recurrent failure of the access with repeat thrombolysis and/or angioplasty.