Scopus is a powerful, easy-to-use tool for searching the scholarly literature on health, life, physical, and social sciences. Scott Library users especially appreciate its cited reference searching as long as the original paper wasn’t published before 1996. It covers over 15,000 journals including 100% of the journal titles covered in MEDLINE, but that is not the same as saying it has all of MEDLINE. MEDLINE journals are only comprehensively included back to 1996.
They’re currently doing an extensive backfill program, but for now don’t assume that you’ve searched MEDLINE with a Scopus search.