Dr Kevorkian, 67, a retired pathologist, could have received four years in prison and been fined $2,000 (pounds 1,300) on each count had he been convicted of violating Michigan's now-expired law against assisting in a suicide. It was his second acquittal in two years.
The patients, one of whom had Lou Gehrig's disease and the other bone cancer, died by breathing carbon monoxide through a mask in a suburban Detroit apartment rented by Dr Kevorkian. The verdict came two days after a ruling by a US federal appeal court declaring a constitutional right to die which has divided American doctors and set the scene for a national debate over the issue of assisted suicide.
The decision was a virtual invitation to the Supreme Court to step into an area of medical ethics that pits the sanctity of life against personal freedom of choice, legal experts said.
The Ninth Circuit Court of Appeals in San Francisco declared on Wednesday that a mentally competent, terminally ill adult "has a strong liberty interest in choosing a dignified and humane death rather than being reduced at the end of his existence to a childlike state of helplessness, diapered, sedated, incompetent".
The ruling, in a case involving three terminally ill patients, all of whom have since died, applies to nine western states from California to Alaska.
The court overturned local statutes banning assisted suicide and said doctors, pharmacists and family members who helped a patient to an early death were not to be prosecuted. Though polls suggest most US doctors favour legalising assisted suicide, the American Medical Association attacked the ruling, as did some churches. Right-to-life groups raised the spectre of bungled mercy killings and of people pushed into choosing death by the pressure of medical bills or impatient family members.