The study aims to identify the reality of the approved bibliographic records in the automatic catalog of the Mosul Studies Center Library and to reveal the accuracy of the application of the MARC 21 standard on them in terms of the accuracy of choosing the appropriate crown, indicators and sub-fields, the study relied on the analytical descriptive approach, by selecting a random sample of bibliographic records consisting of 450 records from the total number of records the catalog which numbers 890 records and analyzing the minimum number of fields must to be included in the bibliographic record and get acquainted accuracy and quality of the records in terms of adherence to the application of the MARC standard and detecting errors and deficiencies in data entry with the aim of overcoming them and bringing the displayed recordings to the highest levels of quality.