Doctors have been leaving the medical profession in sharply rising numbers, according to data on applications for insurance benefits. Insurers believe declining morale is a key to these early retirements.

One factor cited is their growing anger and frustration with the demands of health maintenance organizations -- under which they feel more like employees than entrepreneurs. But the rules of their profession have obviously changed in other ways as government programs exert increasing pressure on them.

Also, they are under constant threat of malpractice suits.

• A Louis Harris poll sponsored by the Commonwealth Fund last year found that only one physician in four was very satisfied with the practice of medicine.

• More than one-third were somewhat or very dissatisfied.

• Some professionals point to "unbelievable hassles" under managed care systems, disrespect, attacks on professional dignity and the doctor-patient relationship, as well as an "enormous amount of unnecessary paperwork."

• The emotional blows are said to be all the greater after grueling years of sacrifice and deferred gratification -- in medical school and low-paying residencies -- followed by late nights and weekends on call.

One result has been a rise in applications for disability benefits. For example, a surgeon who must contend with arthritis or other ailments will more readily give up his practice and apply for insurance benefits.

This has led insurance companies to downgrade surgeons on their rankings of occupation from the most desirable to insure to the least attractive. For disability insurance purposes, surgeons now rank among dispatchers and warehouse foremen -- just one step up from butchers, waitresses, locksmiths, street-cleaning supervisors, cable-TV workers and ticket-takers at ballpark gates.