A congressional subcommittee, a District of Columbia government agency and a hospital group here are beginning preliminary investigations into transfers of patients among hospitals in the city.

"We will start out by looking at how payment affects treatment," said Kitty Myers, special assistant for health on the House Interstate and Foreign Commerce oversight and investigation subcommittee.

Myers said the inquiries follow publication of an article in The Washington Post revealing that nine of 10 patients transferred to D.C. General Hospital from private hospitals have no health insurance.

In addition, the city's State Health Planning and Development Agency has asked D.C. General for its records of transfers. The D.C. Hospital Association also is beginning an investigation of the situation following publication of the stories about the transfers and the recent case of a man who died 55 minutes after a nurse at Capitol Hill Hospital ordered police to remove the man from the hospital's emergency room. The man subsequently was taken to D.C. General, where he was pronounced dead on arrival.

Howard B. Smith, 28, suffered 10 rib fractures, severe internal bleeding and a lacerated liver in a traffic accident, according to a city medical examiner's autopsy. D.C. police reported a nurse at Capitol Hill said Smith had only three rib fractures and could be discharged.

A spokesman for Mayor Marion Barry said Barry has told Capitol Hill that tax-free institutions -- such as Capitol Hill -- endanger this status if they do not provide equal access to service to all.

Capitol Hill, which has acknowledged that Smith was treated at the hospital but otherwise refused comment, yesterday released the text of a letter to Barry in which it said it had retained outside investigators to look into the incident and asked the mayor to make available to the hospital all police and fire department records bearing on the Smith case.