Objective: To assess effects of bisection nephrotomy on renal function, size, and morphology in cats over a period of 12 weeks. Study Design: Controlled, randomized, blinded experiment. Sample Population: Ten adult female cats. Methods: Glomerular filtration rate (GFR), as determined by quantitative renal scintigraphy using 99mTc-DTPA, urinalysis, urine culture, and sonographic measurement of renal size were performed pre-operatively. A left or right nephrotomy (five randomly assigned cats in each group) was performed. Total and individual kidney GFRs were determined in each cat 2, 28 and 84 days post-operatively. Both kidneys were measured sonographically 28 and 86 days postoperatively and an ultrasound-guided biopsy of each kidney was obtained 86 days postoperatively. Results: No significant differences in mean GFR and kidney size of the operated versus un-operated kidneys were observed at any time period. Individual GFR and renal size of all except one of the cats remained within normal limits. Two additional cats had evidence of transient ureteral obstruction in the immediate post-operative period. No significant histologic abnormalities were observed in any biopsy. Conclusions: Bisection nephrotomy in normal cats did not adversely affect renal function or morphology over the three month post-operative period. Clinical Relevance: Bisection nephrotomy can be safely performed in normal feline kidneys without causing a significant deleterious effect on renal function. Studies in animals with pre-existing renal insufficiency are needed to insure no adverse effects would occur in clinical cases where this surgical procedure is warranted. / Master of Science