Abstract: Treprostinil diolamine sustained release (UT-15C SR) is being evaluated as an oral therapy for pulmonary arterial hypertension. This study evaluated the pharmacokinetics (PKs) of treprostinil following administration of UT-15C SR in subjects with end-stage renal disease (ESRD) compared with healthy subjects with normal renal function (NRF) and the effect of hemodialysis on the PK parameters of treprostinil. Eight ESRD subjects (requiring dialysis, mean creatinine clearance = 11.5 mL/min) received 2 single doses of 1 mg of UT-15C SR (separated by 2 weeks), with the first dose given immediately after dialysis and the second given 4 hours before the start of dialysis. Eight NRF subjects received a single dose of 1 mg of UT-15C SR. The median Cmax, AUC0–inf, and t1/2 of treprostinil were 680 pg/mL, 3240 hours⋅pg/mL, and 2.35 hours, respectively, in ESRD subjects dosed after dialysis and were 551 pg/mL, 3152 hours⋅pg/mL, and 2.05 hours, respectively, in ESRD subjects dosed before dialysis. In comparison, corresponding values were 730 pg/mL, 3726 hours⋅pg/mL, and 3.54 hours, respectively, in NRF subjects. UT-15C SR of 1 mg was well tolerated by NRF and ESRD subjects. The most frequent adverse event was headache and nausea. There was no substantial difference in treprostinil PKs between ESRD and NRF subjects following administration of UT-15C SR tablets. Hemodialysis did not have clinically important effect on treprostinil PK in ESRD subjects.