This paper analyzes the effect of changes in accounting policies and criteria on consolidated equity at January 1st 2008 among Spanish unlisted groups that did not implement the International Financial Reporting Standards (IFRS), following the revision of the accounting rules implemented through the new General Accounting Plan and the explanatory note published by the Institute of Accounting and Accounts Auditing (ICAC) on the standards for the presentation of consolidated financial statements. In addition, we evaluate the effects of the transition to the new rules, taking into account the size of each group. To do so, we analyzed the consolidated annual accounts of the 100 largest Spanish firms which have been prepared in accordance with applicable Spanish regulations, by seeking significant differences between equities under the two sets of standards. The results obtained show there has been no significant impact on the consolidated net assets of Spanish groups that have not implemented the international rules regarding the transition to new accounting standards for 2007-2008, and therefore that the information, by enabling comparability, is useful for users. Therefore, the decision by Spanish Government to allow groups that do not implement the IFRS not to present comparative information can be considered to have been correct, as this has facilitated the transition to the new standards without provoking comparability costs and troubles of presentation and conversion. (C) 2013 ASEPUC. Published by Elsevier Espana, S.L.U.