Class of 2015 Abstract / Objectives: To compare and evaluate effects on kidney function of mannitol dieresis versus saline diuresis on kidney function with cisplatin therapy. Methods: Patient charts documented between January 2010 and July 2013 were obtained and reviewed from a database of a university associated medical center. The patient’s lowest creatinine clearance (CrCl) and potassium levels during any time in therapy were compared against the baseline. Statistical testing for primary and secondary outcomes was calculated using the Independent-Samples T-Test. Results: A total of 140 patients were reviewed – 68 patients were included in the mannitol arm, 72 in the saline arm. All baseline characteristics reviewed were not statistically different between groups except for sex, which was skewed towards males in the saline arm of the study. Baseline CrCl was 97.14 ml/min in the mannitol arm, and 93.69 ml/min in the saline arm (p=0.91). The average change in CrCl was found to be -16.72 ml/min (95% CI, -21.85 to -11.59) in the mannitol arm, -14.00 ml/min (95% CI, -18.82 to -9.20) in the saline arm; this was not statistically different (p=0.41). There was an average change of -0.31 mmol/L in blood potassium levels in mannitol patients, and a change of 0.014 mmol/L in saline patients; this was found to be significantly different (p<0.01). Conclusions: In this single-center retrospective study, there appeared to be no benefit in using mannitol diuresis over saline diuresis. The use of mannitol incurs additional cost and place additional restrictions on administration.