Class of 2011 Abstract / OBJECTIVES: The purpose of this study is to assess three published aminoglycoside dosing protocols (large-dose extended interval), to predict peak and trough concentrations of these protocols and to determine the percentage of patients with peak and trough concentrations within each protocol’s specified ranges. METHODS: This study is a retrospective analysis of clinical data. A database of 515 patients is used to analyze the three different protocols. The variables in this database encompass patients’ age, height, actual body weight (ABW), sex, k, Vd, and dose. From these data, patients' peak and trough concentrations were determined using the three large large, extended interval dosing protocols. RESULTS The results showed Nicolau protocol with the most potential of the three protocols. It had the highest percentages of patients with peak above 15 mg/L and a trough less than 0.5 mg/L. It also had the highest average peak of 19.1 mg/L with 69.9% of patients meeting the protocol’s specified peak range of 13 to 23 mg/L. CONCLUSION: The three examined protocols all showed a percentage of patients within the desired range. Of the three, Nicolau protocol I showed promising results with highest average peak, lowest average trough and high percentage of patients with concentrations within desired ranges. Its percentages above 15 mg/L and less than 0.5 mg/L are greater than protocols II and III. Nicolau dosing protocol may be best in achieving high peak and low trough concentrations.