Objectives. To evaluate the utility of the porcine and canine models for collecting system closure after partial nephrectomy involving violation of the renal collecting system. Advanced surgical technologies and novel techniques for performing laparoscopic partial nephrectomy are frequently evaluated in an animal model. Methods. After evaluation of the upper urinary tract with retrograde pyelography, laparoscopic partial nephrectomy, including violation of the renal collecting system, was performed in 8 domestic pigs (group 1) and 2 dogs (group 2) with documented normal upper urinary tract physiology. No collecting system closure was performed. Subsequently, in an attempt to generate an adequate model for renal collecting system closure, 6 pigs (group 3) underwent partial obstruction of the proximal ureter before laparoscopic partial nephrectomy without collecting system closure. After 3 weeks, the animals underwent evaluation, including retrograde pyelography, and were killed for histopathologic evaluation of the upper urinary tracts. Results. Despite documented transection of major calices in all animals, none with physiologically normal upper urinary tracts developed urinomas. After partial occlusion of the proximal ureter, all pigs had hydronephrosis, but only one of six developed a urinoma. Conclusions. The porcine and canine models are inadequate for evaluating renal collecting system closure after partial nephrectomy. Our high-pressure partial occlusion model was similarly inadequate. The limitations of these animal models should be considered when reviewing published data regarding technologies for partial nephrectomy. Future data regarding novel technologies for partial nephrectomy should also be carefully considered before clinical application.