As many as one in 50 teenagers still wet the bed, research has suggested.
Most parents believe bed wetting is normal until age five
When Hong Kong scientists quizzed 16,500 children aged five to 19, 3% reported bedwetting at night, one in five of whom had daytime incontinence.
The British Journal of Urology study found bedwetting was less common as children got older, but the proportion with severe problems grew with age.
Some 82% of young people aged 11-19 with problems wet the bed more than three times a week.
This was double the rate seen in children aged five to 10.
Bedwetting, or primary nocturnal enuresis, has various underlying causes - such as a small bladder capacity, instability during sleep and a failure to wake up when the bladder fills up.
The joint team from the Chinese University of Hong Kong and the Prince of Wales University Hospital said children and adolescents who wet the bed at night also showed a similar pattern of daytime incontinence.
Some 32% of 11-19-year-olds with problems reported daytime incontinence - almost double the 15% rate seen among five to 10-year-olds who said they had a problem.
But overall, by the age of 19, only 3% of boys and 2% of girls were still wetting the bed.
Lead researcher Professor Chung Yeung, who is also president of the International Children's Continence Society, said: "Bedwetting showed a general reduction as children got older.
"However, this reduction was much greater in those with mild symptoms who wet the bed three or less times a week, compared to those with severe problems who were wetting the bed every night.
"Just over 14% of five-year-olds who wet the bed did so seven nights a week.
"By the age of 19, severe bed wetting accounted for over 48% of teenagers who were still wetting the bed."
He said the findings challenged the myth that bed wetting always gets better as the child gets older.
The research paper said that in China, as in western Europe, bedwetting is considered normal up to the age of five and parents do not tend to seek medical advice unless it continues to a late age.
However, this may be too late for some children with persistent problems.
"These latest findings underline the importance of seeking help for children with severe bedwetting problems, especially if they continue into adolescence.
"If these individuals are left untreated, the evidence suggests they will continue to experience ongoing problems when they become adults," said Professor Yeung.
The paper added that bed wetting was as prevalent in western youngsters is it is among Hong Kong Chinese schoolchildren.
An expert in the field, consultant clinical psychologist Dr Richard Butler of Leeds, said the figure of one in 50 teenagers wetting the bed was a high one.
He said that in Britain studies had shown around 2.5% of younger children regularly wet the bed.
Dr Butler said: "I completely agree that there are actions and interventions that can be taken at a young age.
"But most things that parents try to do, like restricting drinks, do not seem to work.
"If parents work on encouraging their children to drink more and work on regular toileting in a planned way, this tends to be more effective."