The use of a urinary bladder catheter in patients having a total hip arthroplasty is controversial. Universal insertion of an indwelling catheter before a total hip arthroplasty, and insertion of a catheter postoperatively as necessary, are accepted variations of care. From 1993 to 1999, 719 patients having primary, unilateral total hip arthroplasties were randomized by surgeons into two groups: a group of patients who had universal preoperative insertion of an indwelling bladder catheter (340 patients) and an observation group who had catheterization as needed (379 patients). Catheterization was required for 295 of these 379 patients (77.8%). Patients were followed up using a total hip arthroplasty database, which recorded all complications. Six patients (1.8%) in the universal catheter insertion group had a urinary tract infection develop. Nine patients (2.4%) in the catheter as necessary group had a urinary tract infection develop. There was no significant difference in incidence of urinary tract infections between the two groups. Female gender and increasing age were associated with a higher incidence of urinary tract infection in both groups. The average length of stay in the hospital for the universal catheter group was 4.8 days, and the average length of stay for the catheter as necessary group was 4.5 days. There was no significant difference in length of stay in the hospital between the two groups. The universal catheter group had an average 590 dollars higher hospital cost for their total hip arthroplasties, which was significant. Routine preoperative bladder catheterization may not be warranted in patients having total hip arthroplasties. Postoperative catheterization as necessary may be more cost effective.