BOSTON, SEPT. 9 -- Gov. Michael S. Dukakis, in an effort to provide health care for the uninsured and reduce medical costs for many businesses, today outlined a plan that could make Massachusetts the first state to guarantee health care for residents.

"This is a historic day in the commonwealth," Dukakis said in announcing a legislative package that is to be filed Friday and would assure medical care for the state's 593,000 people under age 65 who have no health insurance.

Dukakis, a Democratic presidential contender, invoked the memory of President Harry S Truman, who proposed a national guarantee of health care, and said he hopes that his Massachusetts plan will lead to a federal program for 40 million Americans with no health insurance.

"The best policy, obviously, is to have this at the national level," Dukakis said.

Under his plan, employers in existence for more than three years would be required to provide health insurance to employes and dependents. That would cover the vast majority of those without health plans, since 73 percent of the state's uninsured are employed or are dependents of workers.

The requirement cannot take effect unless the state receives a federal exemption from the Employe Retirement Income Security Act of 1974, which prohibits states from forcing private businesses to offer health insurance.

Dukakis said state officials will work with Sen. Edward M. Kennedy (D-Mass.) and Rep. Brian J. Donnelly (D-Mass.) to obtain the exemption after state legislative approval of his package, which he hopes to have by Oct. 1.

The plan would cover, with

state-purchased insurance, those who are unemployed and do not receive health care through welfare.

A new state agency, the Massachusetts Health Partnership, would buy the insurance with money from several sources, including a 9.1 percent surcharge on hospital bills, according to Matt Fishman of the state's Executive Office of Human Services.

Currently, medical bills for those without health insurance are paid with proceeds from a 13 percent hospital bill surcharge, which is paid only by companies offering health insurance.

John D. Crosier, president of the Massachusetts Business Roundtable, an organization of 55 of the state's largest companies, said he had not yet read the proposal or taken a position on it. But he praised Dukakis for trying to distribute health-care costs more equitably. "Right now, those who provide the insurance pay the cost for those who don't," he said.

If the state does not receive a federal waiver by Jan. 1, 1989, Dukakis said he plans to require employers not offering health insurance to contribute to a pool to be used by the state to buy health coverage for workers whose employers do not offer it.