Brazilians are holding a referendum on 23 October on whether to ban the sale of firearms and ammunition to civilians. The authorities say it is the world's first nationwide vote on guns, and that it could set a precedent for campaigns in other countries.
Last year, 36,000 people were killed with firearms in Brazil
The BBC News website looks at some of the key issues surrounding the referendum.
Why is the vote important for Brazil?
Brazil has the second-highest number - behind Venezuela - of gun-related deaths in the world per capita, outstripping many war zones.
A recent United Nations report said more than half a million people were killed by guns in Brazil between 1979 and 2003. Firearms are believed to be the biggest cause of death among Brazil's youth.
Heavily armed drug gangs control slums, or favelas, and regularly engage in fights with outgunned police.
The cities of Sao Paulo and Rio de Janeiro are traditionally associated with gun crime.
Last year, 36,000 people were killed with firearms - 99 deaths per day.
What exactly is to be decided?
Over 120 million people are expected to take part in the referendum - voting is compulsory in Latin America's largest country.
If Brazil votes in favour of the ban, all sales of guns and ammunition to civilians will be halted, leaving those who already have registered firearms without bullets.
Police, judges, military personnel and private security firms will still be able to buy them.
According to official figures, there are 17 million guns circulating in the country, 90% of them in the hands of civilians and half of them unregistered. Over 60,000 firearms are sold every year.
What do Brazilians think about the ban?
Months ago opinion polls suggested that most people were in favour of such a ban, but the latest survey shows a slight advantage of the "no" vote, so results of the referendum look very uncertain.
Even the government is divided. President Luiz Inacio Lula da Silva endorses the prohibition. But his vice-president and defence minister, Jose Alencar, says it would encourage criminals.
What do supporters and opponents of the ban say?
Both have waged fierce campaigns on radio and television and in the press.
Those wanting to see gun sales banned say it will contribute to cutting down the violence that has given Brazil an annual death toll from firearms that is higher than many war zones.
But advocates of gun ownership say the prohibition would not reduce the arsenals held by drug gangs and other criminals, because it is not addressing the problem of illegal guns smuggled into Brazil from neighbouring countries.
They also claim that the right to legitimate defence is an essential right. Some Brazilians say that they will vote against the ban in order to keep protecting themselves from street crime.
What has the government done so far to fight gun-related crime?
A law passed by Congress recently has placed restrictions on who can buy and carry guns, and over the past year nearly half a million weapons have been handed in to police and destroyed under a buy-back scheme.
This year Brazil reported a fall in the number of deaths caused by firearms for the first time in 13 years.
The government put the improvement down to its own disarmament policies.