This study investigates the use of polarimetric variables for estimating hail size.  Archived data from the KOUN polarimetric radar in Norman, Oklahoma are obtained for three hail-producing events during 2004:  24 May, 29 May, and 2 June.  A total of 45 hail reports are used for analysis, including hail sizes ranging from 0.75” to 4.25”.  Horizontal and vertical structures of reflectivity at horizontal polarization (Z_H), differential reflectivity (Z_DR), and correlation coefficient (r_HV) associated with these reports are examined using Interactive Data Language (IDL) programs.  Comparison of these images allow for the hail to be categorized into two groups based on Z_DR and r_HV signatures: hail less than 1.75” in diameter and hail 1.75” or higher in diameter.  RHI images reveal differences in the vertical structures of these categories; extended columns of low Z_DR and r_HV are observed for the larger hail.  Also, vertical profiles of these variables show a more significant decrease in r_HV below the melting layer for hail 1.75” or larger.  Box-and-whisker plots and discriminant analysis are then used to determine the ability of Z_DR and r_HV to distinguish between the two categories.  Although Z_DR appeared promising for estimating hail size, the discriminant analysis revealed that r_HV is the best variable to discriminate between the categories.