Temporary catheters are still essential for acute dialysis access but their performance has not been compared in randomized trials. We conducted a randomized trial of our standard catheter and a newly designed catheter. The primary outcome was maximized blood flow over the entire use of the catheter. Seventy-six patients provided maximum blood flows. The new catheter provided an average blood flow of 349 ml/min and the standard catheter provided flows of 320 ml/mm (p=0.09). Lumen reversal occurred in 56.8% of dialysis sessions with the standard catheter compared to 27.4% with the new catheter (p<0.001). Left-sided internal jugular catheters and catheters inserted in females provided 103 ml/min and 36 ml/min less blood flow, respectively, compared to right sided catheters and catheters placed in males. Approximately 20% of catheters were removed for poor blood flow. Left sided catheters and catheters in females were more likely to need removal for malfunction but catheter design did not influence removal rates.