The collection “Old-printed, rare and valuable books in foreign languages (XVI-XX c.)” is one of the most valuable collections of special and rare books of the University Library. This collection includes fundamental scientific publications in various scienfitic fields, such as history, classical studies, philosophy, mathematics, law and many more. This collection is recognized for its exceptional scientific significance and is an invaluable importance for university researchers. The collection “Foreign old-print, special and rare editions (XVI-XX century)” serves as a basis for academic teaching at the Sofia University, and provides scientific opportunities for research of the history of science.