A total of 172 "suicide tourists" travelled to Zurich during 2012 for medical assistance to die at the Dignitas clinic, according to a preliminary analysis published in the Journal of Medical Ethics.
This is almost double the number in 2009 which saw 86 visitors seeking assisted death, reports AFP.
The highest numbers were from Germany and the UK. The age varied from 23 to 97, with the average being 69; nearly 60% were women.
Death in most cases was caused by administering sodium pentobarbital.
A total of 611 people from 31 countries had come to Switzerland from 2008 to 2012, seeking death at the clinic of the non-profit organisation, Dignitas.
Of this, Germany led with 268 and the UK with 126, 66 French, 44 Italians, 21 Americans, 14 Austrians, 12 Canadians and eight each were from Spain and Israel.
The numbers had initially gone down from 123 in 2008 to 86 in 2009 but picked up again in 2012, said a Wall Street Journal report.
According to Julian Mausbach, a study author and researcher at Zurich University's Center of Excellence for Medicine, Ethics and Law, this upsurge could be due to hazy regulations around assisted suicide.
Swiss law allows assisted deaths as long as it isn't for selfish reasons. The four right-to-die-organisations in the country go by strict criteria that include terminal illness, unbearable suffering, a consistent wish to die and sound judgment.
The swelling numbers raise many ethical and legal questions, said Dr Mausbach. One was the need to examine why patients travel such distances to end their lives, when their country bans such deaths.
The other aspect was that of cost. At around £1,800 per person, how and whether the nation should foot the bill is a subject of debate.
Euthanasia is legal in the Netherlands, Belgium and Luxembourg. Assisted suicide is legal in Switzerland, Germany, Albania, Colombia, Japan and in the US states of Washington, Oregon, Vermont, New Mexico and Montana.
Britain is still debating the Assisting Dying for the Terminally Ill Bill.