There are six right to die organisations in Switzerland, of which four permit nationals from other countries to use their services.
Citizens from Germany and Britain make up the bulk of the numbers with neurological conditions such paralysis, motor neurone disease, Parkinson's and multiple sclerosis - accounting for almost half of the cases, the findings showed.
Virtually all the deaths were caused by taking sodium pentobarbital.
Four people inhaled helium - deaths which were widely publicised and described as "excruciating", researchers added.
"The reasons for the subsequent reported uptick are not known but may be due in part to loose regulations surrounding assisted suicide in the country," said Julian Mausbach, a study author and researcher at Zurich university's centre of excellence for medicine, ethics and law.
To know more on "suicide tourism", researchers searched the databases of the Institute of Legal Medicine in Zurich for information on non-Swiss nationals who had been helped to take their own lives between 2008 and 2012.
The search revealed that 611 people who were non-resident in Switzerland had been helped to die between 2008 and 2012.
Their ages ranged from 23 to 97, with the average being 69; over half (58.5 percent) of the "tourists" were women, who were 40 percent more likely to choose assisted suicide in Switzerland than men.
In all, residents from 31 different countries were helped to die in Switzerland between 2008 and 2012, with German (268) and Britain (126) nationals making up almost two thirds of the total.
The non-profit Dignitas, one of the best-known groups to support patients' right to die, was involved in nearly all the cases of suicide tourism in the study.
In Zurich, researchers found 172 cases of so-called "suicide tourism" in 2012, up from 123 in 2008.
A Swiss law allows assisted suicide as long as it is not motivated by selfish reasons.
"Switzerland is doing the job that is not being done elsewhere because the regulations in other countries do not offer the opportunity," Mausbach added.
The preliminary analysis appeared in the Journal of Medical Ethics.