Joseph C. McLaughlin, 50, owner of McLaughlin Oldsmobile in Capital Heights, one of the nation's largest black-owned companies, died of a heart attack yesterday at Greater Southeast Community Hospital.

Mr. McLaughlin, a prominent business and civic leader, was active in the affairs of the D.C. Republican Party and was president of the D.C. Chamber of Commerce.

In the most recent survey made by Black Enterprise magazine, Mr. McLaughlin's automobile dealership was ranked No. 52 on a list of the nation's 100 largest black-owned companies.

Mr. McLaughlin, who was born in the District, grew up in a home in which money was scarce. An incident in his boyhood, he once said, fostered the determination that enabled him to overcome the obstacles to minority enterprise.

When he was 12, he recalled, his family could not buy him an overcoat. On a bus, on the way to a basketball game, he wore an oversized, ill-fitting coat that had come from his mother's boss. Other boys on the bus were derisive.

"I made up my mind at that moment that nobody would ever laugh at Joe McLaughlin again," he said.

In 1982, according to Black Enterprise, McLaughlin Oldsmobile registered $8 million in sales. Last year, according to the survey, the figure rose to $14.5 million.

Before opening his dealership in 1976, Mr. McLaughlin owned the Black Nugget restaurant in Washington. He had also worked in the computer field and operated a computer company in the late 1960s.

He graduated from Armstrong High School here, and attended American University and the Los Angeles Trade and Technical College.

Mr. McLaughlin, a District resident, was a former treasurer of the D.C. Republican Central Committee, and twice ran unsuccessfully for the post of Republican national committeeman. He had been appointed chairman for the forthcoming United Negro College Fund telethon.

In August, he was sworn in as a member of an official commission formed to bring major league baseball back to Washington, and he was recently named by Mayor Marion Barry to the D.C. Local Development Corp.

Survivors include his wife, Katye H., and two children, Brian David and Bridget Dianne and his mother, Sarah McLaughlin Butler.