"We have completed all the studies," Vladimir Uiba, head of Russia's Federal Medical-Biological Agency (FMBA), told at a news conference.
"The person died a natural death and not from radiation."
Arafat's remains were exhumed last year and some 60 samples were taken and divided between Swiss and Russian investigators as well as a French team carrying out a probe at the request of Arafat's widow, Suha.
The French have also ruled out poisoning, while the Swiss report said high levels of radioactive polonium indicated third party involvement in Arafat's 2004 death.
Uiba told reporters today that his agency had not received any requests from the Palestinians to conduct a repeat examination.
"We've completed an expert evaluation, and everyone agreed with us. Moreover, even the Swiss withdrew their statements and agreed, and the French confirmed our conclusions," Uiba told reporters.
The Russian agency in October doubted a report published in The Lancet, saying that Swiss radiation experts had found traces of polonium on Arafat's clothing.
Uiba was reported as saying at the time that Arafat could not have been poisoned by polonium but the agency quickly denied issuing any conclusions about the leader's death.
