The endoscopic correction of vesicoureteral reflux is a well accepted procedure. However, the search for the ideal injectable substance continues. We compared the persistence of autologous free fat transplants from the perivesical fat pad and the abdominal wall to the bladder submucosa in an animal model. Perivesical fat consistently showed greater persistence than abdominal wall fat over time. Perivesical fat may be an ideal substance for endoscopic injection when treating vesicoureteral reflux.