Dr. Vladimir Clain-Stefanelli, 68, the head of the National Numismatic Collections at the National Museum of American History and a noted authority on coins, currencies and medals, died of an embolism Oct. 19 at Georgetown University Hospital, where he had undergone heart surgery.

Dr. Clain-Stefanelli, who joined the staff of the Smithsonian Institution in 1956, is credited with having made the collections for which he was responsible among the most important in the world. His wife, Elvira, an authority on numismatics in her own right, was his colleague in this work.

Some of the additions that were made during Dr. Clain-Stefanelli's tenure are a collection of gold coins assembled by the late Josiah K. Lilly Jr., a pharmaceutical magnate, which is particularly strong in U.S. and Latin American examples, and the Willis H. DuPont collection, which was originally assembled by the Grand Duke Georgi Mikhailovich Romanov. It is the most complete collection of Russian coins outside the Soviet Union.

Among the exhibitions organized by Dr. and Mrs. Clain-Stefanelli were the Hall of Numismatics, which was opened when the Museum of History and Technology, now the Museum of American History, was established in 1964; the Hall of Money and Medals, and "Two Centuries of American Banking," a Bicentennial exhibition that opened in 1975. In contrast to the usual treatment of numismatics as metal works of art, these exhibitions presented the materials as integral parts of cultural and economic progress.

Dr. Clain-Stefanelli was a specialist in the historical documentation of U.S. coinages and in the coinages of Greek colonies on the western Black Sea coast and southeast European issues of the 15th and 16th centuries.

His books include a four-volume catalogue of the Alexander Magnaguti Collection, which was published in Rome from 1949 to 1951; "History of the National Numismatic Collections," published in Washington in 1968, and, with his wife, "The Beauty and Lore of Coins, Currency and Medals" (1974) and "Chartered for Progress: Two Centuries of American Banking" (1976).

Dr. Clain-Stefanelli was born in the Romanian city of Czernowitz, then a part of the Austro-Hungarian Empire, later part of Romania, and since 1940 a part of the Soviet Union. He received bachelor's, master's and doctoral degrees in philology and archeology at the university there.

He moved to Rome and later worked for the Vatican. In 1949, he came to the United States and was a consultant to firms in Rome and New York. He moved to the Washington area when he joined the Smithsonian. He lived in Arlington at the time of his death.

Dr. Clain-Stefanelli began at the Smithsonian as curator of numismatics. In 1974, he was named chairman of the department of applied arts at History and Technology. In 1977, he was appointed chairman of the department of national history. When the museum was reorganized in 1980, he continued as head of the National Numismatic Collections. He was an adviser to the Treasury Department and other government agencies.

He was a member of the American and Royal numismatic societies, a former governor of the Archaeological Institute of America and president of its Washington chapter, and a member of the Cosmos Club.

In addition to his wife, of Arlington, survivors include a son, Alexander, also of Arlington.