1 EXHIBIT 23.3 Consent of Ernst & Young LLP, Independent Auditors We consent to the reference to our firm under the caption "Experts" in the Registration Statement (Form S-4) and related Prospectus of AdvancePCS (formerly Advance Paradigm, Inc.) for the registration of $200,000,000 of senior notes, and to the incorporation by reference therein of our reports dated January 14, 1999 and April 21, 2000 (except Note 12 to the April 21, 2000 report, as to which the date is June 15, 2000), with respect to the consolidated financial statements of PCS Holding Corporation and Subsidiaries included in the Advance Paradigm, Inc.'s Form 8-K/A dated October 26, 2000, filed with the Securities and Exchange Commission. /s/ ERNST & YOUNG LLP Phoenix, Arizona April 16, 2001