Patients who undergo percutaneous transluminal coronary angioplasty (PTCA) by the femoral approach are usually required to lie flat in bed for 6 to 24 hours, which may result in significant discomfort. This study was performed to evaluate the safety and benefit of a flexible sheath that enables patients to sit at a 60-degree angle while the sheath is in place in the femoral artery. Sixty patients were randomly assigned to receive either flexible or nonflexible sheaths before PTCA. Patients with flexible sheaths were allowed to sit at an angle of 60 degrees after the procedure. Heparin management was the same in both groups. Frequency of calls to nurses for back pain was recorded for both groups. For analgesia, nalbuphine was administered in 2-mg increments. All sheaths were removed the day after the procedure. Femoral ultrasound was used to detect groin complications (hematoma, pseudoaneurysm, or arteriovenous fistula) and was performed in all patients. Baseline characteristics were similar in both groups. There were no differences in ease of sheath insertion or guide catheter movement through the sheaths. The arterial pressure waveform was not dampened in any of the flexible sheath patients while in the sitting position. Patients with flexible sheaths had fewer calls for back pain and required less nalbuphine than patients with nonflexible sheaths. Groin complications were similar in both groups. In conclusion, by allowing patients to sit up to an angle of 60 degrees, flexible sheaths have a beneficial effect in reducing back pain and the need for analgesics after PTCA.