A Windows program, called WinEpclas, has been developed to calculate and classify wet-chemical and electron-microprobe epidote-supergroup mineral analyses based on the Comission on New Minerals and Mineral Names (CNMMN) of the International Mineralogical Association (IMA-06) nomenclature scheme. WinEpclas enables the user to enter epidote-supergroup mineral analyses in the Data Entry Screen as well as loading previously typed Microsoft (R) Excel files. The program allows the users to type 43 variables of epidote-supergroup mineral analyses in program's data edit section. Mineral analyses are calculated by WinEpclas on the basis of Sigma(A+M+7)=8.0 normalization scheme. However, by selecting the Apply Si=3 Normalization option from the pulldown menu of Si Normalization, epidote formula is renormalized on Si=3 .0 (apfu), if the estimated Si (apfu) content of analysis exceeds 3.05. Using recalculated cations and anions of epidote-supergroup mineral analyses, the program first assigns four epidote subgroups including clinozoisite, allanite, dollaseite, and askagenite and then determines the mineral species based on the dominant cations at A 1, A2, M1 , M2, M3 as well as anions at O4 and O10 sites. All the calculated results by WinEpclas are stored in an output Excel file and, thus it can be used by users for further general data manipulation and graphing purposes. WinEpclas is distributed as a self-extracting setup file, including the necessary support files used by program, a help file, and sample data files.