Nearly a third of Zimbabwe's 5.5 million registered voters are dead, researchers have found.
Others appear to be up to 120 years old, vastly exceeding the country's average life expectancy of 44.
The independent Zimbabwe Election Support Network said the list should be overhauled before elections scheduled for this year.
The report also found that some 40% of voters had moved without updating their voting information.
Officials from the group said such problems open the way for "double voting and other rigging intentions".
Rights groups have accused president Robert Mugabe, 86, and his loyalists of human rights violations and election rigging.
Mugabe has ruled the country since 1980.