The Brazilian Congress has approved a plan for a nationwide referendum on whether to ban the sale of firearms.
Brazilian police have had to contend with well-armed criminals
A majority of lawmakers voted in favour of holding the referendum, which is now expected to take place on 23 October.
Campaigners for a ban welcomed the decision. Brazil has the second-highest number of gun-related deaths in the world, outstripping many war zones.
A recent UN report said more than 500,000 people were killed by guns in Brazil between 1979 and 2003.
Guns are believed to be the biggest cause of death among Brazil's youth.
The bill calling for the referendum was backed by 258 deputies. Forty-eight voted against it.
Rangel Bandeira, a rights group representative, was quoted on the Brazilian senate's internet site as saying the law meant Congress is "in harmony with society... that has been fighting for years to make the country less violent".
However, gun lobbyists say the public needs weapons to defend themselves against criminals who have bypassed existing laws to acquire their guns.
Recent laws have restricted the right to carry a gun to Brazilians in high-risk professions who have no criminal convictions and have passed psychological tests and gun-handling courses.
Anyone caught carrying a gun without a permit risks a four-year jail term.
A disarmament scheme initiated by the government has seen more than 300,000 weapons handed into police in return for cash.