Purpose: Alpha blockade has been well described clinically for expulsion of distal ureteral stone. However, the in-vivo effects of α-blockade on ureteral dynamics during stone passage are not clear. We studied the effects of oral alfuzosin on ureteral pressure and peristalsis in a distally obstructed porcine ureter. Methods: Twenty-four female domestic swine (75-82 kg) were incorporated into the study. The study was powered to detect a 30% difference in distal ureteral pressure, with a secondary endpoint of frequency of ureteral peristalsis. The animals were divided into four equal groups: a control group without α-blockade or ureteral obstruction, a group with α-blockade and no ureteral obstruction, a cohort without α-blockade but with distal ureteral obstruction, and a group with α-blockade and distal obstruction. Peristalsis was measured by a magnetic sensor and ureteral pressure through a 5F ureteral balloon catheter. Observations were recorded for 10-minute intervals every hour for 5 consecutive hours. Results: There was increase in ureteral pressure and peristaltic rate with distal ureteral obstruction (p < 0.01). Alpha blockade did not produce significant changes in the above parameters with or without ureteral obstruction compared with the nonmedicated groups. We observed a 0.2 mm Hg lower increase in change of ureteral pressure during peristalsis compared with resting ureteral pressure (delta pressure) in the treated obstructed model (95% confidence interval: -0.55 -0.10; p = 0.06). Conclusions: In the porcine model, alfuzosin appears to decrease the delta pressure in the distal ureter during obstruction; however, statistical significance was not reached. Further investigation into the in-vivo physiology of medical expulsive therapy is warranted.