John Yarmola, 56, vice president of the Seafarers International Union of North America and a member of the executive board of the AFL-CIO Maritime Trades Department, was found dead Monday at his home in Washington.

The D. C. medical examiner's office said the cause of death was occlusive coronary arterioslcerosis. Colleagues of Mr. Yarmola said he had left work Friday feeling unwell and that his body was discovered after he failed to appear at his office on Monday.

Mr. Yarmola, who was born in Chicago and served in the Navy, began his career with the AFL-CIO in Washington in 1950. He joined the Union Label and Service Trades Department. In the mid-1950s, he helped set up the Maritime Trades Department, which now has 43 national and international unions with 8 million members.

About 1959, Mr. Yarmola was named an international represenative of the Seafarers International. He also became special assistant to its then president, the late Paul Hall.

In the 1960s, in addition to his work with the Seafarers, Mr. Yarmola helped organize a group of Chicago cab drivers who broke away from the Teamsters Union. In 1967, he organized the United Industrial Workers of the Midwest, which represents about 17 industrail shops in the Chicago area. This union was affiliated with the Seafarers and in 1968 Mr. Yarmola was named its president. In the same year, he was elected vice president of the Seafarers.

In 1977, he joined the executive board of the Maritime Trades Department.

Since he began his labor career here, Mr. Armola had maintained home in both Washington and Chicago.

Survivors include his wife, Peggy, one son, Jeff, his mother, Anna Yarmola, and a sister, Marie, all of Chicago, and one brother, Steve, of Washington.