In a decision that hospital administrators contend could result in higher hospital bills across the country, the U.S. Court of Appeals here ruled yesterday that medical residents have a right under federal law to form labor unions.

The 2-to-1 appellate court decison, in effect reversing a ruling by the National Labor Relations Board in 1976, paves the way for residents in private, nonprofit hospitals across the country to form unions and bargain collectively with hospitals for wages, hours and other working conditions.

Although the Physicians National House Staff Association (PNHSA), the national representative for medical residents, has denied that pay is its primary concern, hospital administrators have predicted that a union for residents will result in demands for higher wages and, therefore higher hospital bills.

Congress enafted legislation in 1974 permitting private, nonprofit hospital employes to organize unions under the National Labor Relations Act. Despite language in committee reports and Senate floor debate on the bill making clear the intent to include house staff physicians under the labor act, the NLRB ruled in 1976 that residents still were not covered.

When the PNHSA brought suit in U.S. district court here, Judge Thomas A. Flannery ruled that he lacked jurisdiction and dismissed the suit. The appellate court ruling yesterday said that Flannery was wrong in dismissing the suit. Since Flannery could find he had jurisdiction only if the NLRB has committed a serious error, the Court of Appeals ruling also effectively reverses the NLRB's holding.

Of the 60,000 to 65,000 medical residents (formerly called interns) practicing medicine in academically-affiliated hospitals across the country, about 13,000 now are members of the association, but about half of the total currently can be organized into unions if they so choose.

The remaining 30,000 residents working for public hospitals still are not covered by the labor act and may not form unions unless permitted to do so by federal law.

Residents, whose careers are romanticized in television soap operas, typically work 80 to 100 hours a week for wages ranging on the average from $13,145 for a first-year resident to $17,458 for a sixth-year resident.

The Association of American Medical Colleges, whose litigation before the NLRB precipitated the board's 1976 ruling, declined to comment on the appellate court rulling yesterday. It was not immediately clear whether the board would accept the ruling of appeal it to the Supreme Court.