The BBC reported overwhelming defeat for two initiatives, citing figures from the Swiss news agency SDA.
One ballot question would have imposed a one-year residency requirement for assisted suicide, and the other would have outlawed it altogether.
Assisted suicide has been legal in Switzerland since 1941 if carried out by a non-physician with no vested interest in the death. Only passive assistance, like supplying drugs, is permitted.
About 200 people commit assisted suicide each year in Zurich, many of them foreign "suicide tourists."
One group, Dignitas, says it has helped more than 1,000 foreigners kill themselves, while another, Exit, only works with permanent residents and requires lengthy counseling.
The proposals were supported by the conservative Evangelical People's Party and the Federal Democratic Union but opposed by the larger Swiss People's Party and the Social Democrats.
The government is planning to revisit federal laws on assisted suicide to ensure it is only a last resort for the dying.