A five-year, $450 million fund-raising campaign, billed as the largest in the history of American higher education, was announced today by officials of Johns Hopkins University and Johns Hopkins Hospital.

The presidents of the two institutions told a press conference that the school and hospital are in sound financial health, but that the current explosion in research and technology requires vast new outlays for construction, salaries, equipment and research tools.

"As knowledge expands," said hospital president Robert M. Heyssel, "the resources needed to speed discoveries from laboratory to bedside also expand."

"While some may consider this large a campaign audacious," added university president Steven Muller. " . . . $450 million represents what is necessary and achievable to meet our most critical priorities: faculty and student support, state-of-the-art instrumentation, research support, and construction and renovation of laboratories and classrooms."

Morris W. Offit, vice chairman of the university's board of trustees and head of the development campaign, said that the $450 million goal exceeds any other in the United States. The campaigns that come closest, he said, are by Columbia University in New York, which started a $400 million fund drive two years ago, and Harvard University in Cambridge, Mass., which is just completing a five-year, $350 million drive.

Officials stressed that their campaign will be handled "in-house" by Hopkins administrators and should cost less than if conducted by professional fund raisers.

Other officials said they expect about 60 percent of the $450 million to come from individual donors, 25 percent from foundations and the rest from corporations.

Offit noted that Hopkins' complex here has 77,000 alumni, and "we also are making a special effort to involve [them] and countless friends around the world."

Muller chided American corporations, noting that on the average they give only 1 percent of their earnings to charity.

"One percent simply is not enough," he said. "It's got to be double, and should be 5 percent."

Offit said $120 million of the $450 million will be used to expand the endowments at the institutions, currently $330 million to $350 million at the university and $60 million at the hospital.

Officials said it is too early to give a detailed breakdown for development spending, but that in addition to the $120 million for the endowments, $150 million would go for research and instrumentation, $100 million for current programs and faculty and student support, and $80 million for building construction and renovation.