Retired Chief Judge Nathan Cayton, 78, of the D.C. Court of Appeals, died Saturday at his home in Washington after a long illness.

Although he had retired officially in 1956, Judge Cayton continued to fill in on the bench for ailing and vacationing judges until he was stricken with a heart attack five years ago.

He also served actively as an arbitrator in commercial and labor disputes involving the government and private industry until he becomes ill.

Judge Cayton was born in Washington about two blocks from the offices he later occupied as a judge. He was a graduate of old Central High School and National University Law School, now a part of George Washington University.

He entered a privaye practive here and in 1927, a week after his 28th birthday, was appointed a judge of the old D.C. Municipal Court by President Calvis Coolidge.

At that time, he was the youngest judge ever to have been appointed to judicial office by a President.

When he was appointed, the Municipal Court, which was evolved over the years in the present D.C. Superior Court, heard only civil suits. He later fathered the mall Claims Court and streamlined the Landlord and Tenant Court.

In 1942, when the Municipal Court of Appeals, was organized, he was appointed by President Franklin D. Roosevelt to serve as a member of its three-judge panel. The court provided for the first time for appeals of right in cases tried in District of Columbia courts.

President Harry S. Truman elevated Judge Cayton to the chief judgeship in 1946 and he continued in that capacity for 10 years.

Judge Cayton was known for his humanity as well as his gently sense of humor. His career was characterized by his philosophy that courts of justice must be as accessible to the poor as to the rich.

Later, he once said of his long career on the bench:

"I enjoyed being a trial judge. You don't have to be a legal scholar to be a good trial judge. The lawyers just want you to be right most of the time in matters of the law, and to be always fair and considerate.

"Lawyers won't forgive a judge who thinks he is there to be served rather than to serve and who runs roughshod over them and witnesses. The worst things that can be said about a judge is that he is callous.

"An appellate judge, on the other hand, should be a scholar; that is, he should be willing to study and to learn, but the most important quality is still humaneness."

Judge Cayton was considered a scholar, spending many years on the law faculties of Columbus University, now part of Catholic University, and Htward, National and Benjamin Franklin Universities.

After retiring, he spent much time on such civic and professional projects as the Attorney General's Conference on Court Congestion. He was chairman of the D.C. Bar Association Commission of Legal Aid, which presented recommendations adopted by the Judicial Conference of the D.C. Circuit and resulted in the creation of a new Legal Aid Agency.

Judge Clayton served on special ad-Department and several times was chairman of Labor Department industry committees in Puerto Rico, the Virgin Islands and American Samoa.

He was a member of the National Academy of Arbitrators, had served on the executive committee of the American Arbitration Association and for a number of years had been chairman of the D.C. Bar Association's committee on arbitration.

He also belonged to the American Bar Association, the American Judicature Society, Gamma Eta Gamma leal fraternith and the Order of the Colf.

Judge Cayton never married. He is survived by two brothers, Dr. Leon Cayton and Howard Cayton, of Washington.

The family suggests that expressions of sympathy be in the form of contributions to the American Heart Association.