The number of foreigners travelling to Switzerland for assisted suicides doubled over four years, according to a study published in the Journal of Medical Ethics.
In 2012, 172 foreigners took their lives in Switzerland, which has liberal euthanasia rules, up from 86 in 2009, with citizens from Germany and Britain making up almost two-thirds of the total, the study found.
Assisted suicide has been legal in Switzerland since the 1940s, if done by someone with no direct interest in the death.
"Mercy killing" is also legal in the Netherlands, Luxembourg, Belgium and some areas of the United States, but remains illegal in many countries, pushing some to travel abroad where they can be helped to die without fear of their loved ones, or doctors, being prosecuted.
Courts in Britain, France and the European Court of Human Rights have faced the delicate issue in recent months.
Neurological conditions, such as motor neurone disease, Parkinson's and multiple sclerosis were factors in almost half of the cases examined in the study.
A rise in foreign assisted suicides has provoked heated debate in Switzerland. In 2011, voters in Zurich rejected proposed bans on assisted suicide and "suicide tourism". A year later, the nation voted against tightening controls on the practice.