Lambros D. Callimahos, 66, a renowned concert flutist who became a cryptologist for the National Security Agency, died of cancer Friday at Walter Reed Army Medical Center.

Beginning in 1948, he worked with codes and ciphers for the NSA. During this time he wrote many books and monographs on cryptology for the government, which are still classified. He also contributed articles on codes and ciphers that were published in the World Book Encyclopedia, Collier's Encyclopedia, and Encyclopedia Britannica.

In 1976, Mr. Callimahos received the agency's Cryptologic Literature Award and the Exceptional Civilian Service award.

Born to Greek parents in Cairo, Egypt, he came to this country at the age of 4.

After studying the flute at the Juilliard School of Music in New York City and further study in Paris, he made his debut as a flute soloist in Munich, Germany, in 1934.

Mr. Callimahos toured Europe appearing with symphony orchestras in Britain, France, Austria, Belgium, the Netherlands, Spain, Switzerland, Italy, Hungary, Greece, Latvia, Estonia, Poland and Sweden.

In 1936, he became the youngest professor at the Mozarteum Academy in Salzburg, Austria.

He made his New York debut in 1937 at the Town Hall, and made musical history when he gave an all-flute recital at Carnegie Hall a year later.

Mr. Callimahos continued his interest in the flute during his time with the NSA, and was teaching talented flute students until the time of his death.

His interest in decoding began in Paris in 1934, when he studied cryptolgy at the Sorbonne.

An accompolished linguist, he could speak nine languages and read several more.

He enlisted in the U.S. Army in February, 1941, was later commissioned and served as assistant theater signal intelligence officer for the China-Burma-India theater during World War II.

He remained on active duty in the Army Security Agency until retiring in 1948 with the rank of lieutanant colonel, at which time he joined the NSA.

Mr. Callimahos was past president of the Maryland Association for Retarded Citizens, and was associated with the Rosewood Association.

He is survived by his wife, Helen, of the home in New Carrollton and a son, Andrew, also of New Carrollton.

The family suggests that expressions of sympathy may be in the form of contributions to the Great Oaks Center Auxiliary, 12001 Cherry Hill Rd., Silver Spring.