The purpose of this study is to evaluate the quality of the Serials Union Catalog(UCAT) of KISTI. In examining both MARC records and bibliographic display records of 172 Japanese serials, AACR2R and KORMARC formats were used as the standard rules. Those records were described in the minimum or incomplete level; but had repeated errors in various data fields, which included the incorrect choice of main headings, parallel titles and other titles, the improper use of language codes and related data fields, and the provision of incomplete information, etc. To improve the overall quality of bibliographic database, thorough comprehension and application of cataloging rules and MARC formats are strongly required.