But the threat of a $1.80 fine, under a crackdown due to begin on 1 June, has led to a huge boom in helmet sales - with some vendors selling hundreds a day, particularly the cheaper alternatives from China.
Although the government introduced a decree requiring motorcyclists to wear helmets five years ago, it was largely ignored.
Many people in the country, where the average monthly wage is less than $30, cannot afford the costly $50 for the better helmets - or even the $6 for the cheapest varieties.
But the threat of a $1.80 fine, under a crackdown due to begin on 1 June, has led to a huge boom in helmet sales - with some vendors selling hundreds a day, particularly the cheaper alternatives from China.
The Saigon Times daily reported that one vendor was selling 1,200 helmets a day.
But some reports say many of the of the helmets from China are below standard, and some are actually plastic toy imitations.
"People are learning how to wear a rice cooker," student Nguyen Thu Thuy, 21, told the AFP news agency.
"I can't imagine how I will look like when I'm wearing a rice cooker."
'Deadlier than Aids'
Road accidents have been described as "deadlier than Aids", with an average of 20 people dying daily in traffic accidents.
Of the nearly 8,000 people killed and more than 25,000 injured in traffic accidents last year, well over half - 64.5% - involved motorcycles, the National Committee for Traffic Safety has said.
Less than 3% of the riders were wearing helmets.
One survey last year found that only 5% of motorcyclists owned helmets - and furthermore, only half of them actually wore the helmets.
Many Vietnamese complain that helmets would be uncomfortable in the heat country's heat and humidity, while some say they are impractical to carry around into restaurants and wedding receptions.
Another main reason cited was that they feared looking stupid.