Gap-year programmes risk becoming outdated and "colonial", while more students from developing nations are volunteering in the UK, a charity says.
Prince Harry spent part of his gap year in Lesotho, southern Africa
VSO said programmes were often more interested in how UK youngsters could help poor communities, rather than in what they could learn from them.
And some paid little attention to whether they helped in the long run.
VSO said more students from developing nations were also taking a gap year - and often volunteering in the UK.
The charity said some 500 young people from developing nations had come to the UK over the past six years to take part in volunteer programmes as part of its Global Xchange programme.
The programme, run in partnership with the British Council and CSV, also enables British youngsters to travel abroad.
VSO director Judith Brodie said: "The prevailing attitude to gap years risks becoming outdated and colonial as it tends to focus on how British youngsters can help poor communities overseas, rather than on what we can learn from them.
"Some gap-year providers seem to pay little attention to whether young people are actually making any real long-term difference to the communities they are working in. It's an 'all about us' attitude."
Those coming to the UK participate in one of two programmes - in Glasgow and Bradford.
A VSO spokeswoman said: "It is not just rich countries that are able to send volunteers to poorer countries.
"There are things in the UK that volunteers can help us with. Issues such as child poverty or how we look at asylum-seekers."
Ennik Fajaarwati, 23, from Surabaya in Indonesia, is one of nine Indonesian young people spending part of their gap-year in Glasgow.
She said: "At home, we never see any of the problems in Britain on television. It's as if they don't want to touch the bad side.
"We've created the stereotype that western countries have a modern life and society and won't need anything. But although everything is hi-tech here, it seems there are a lot of things for us to do."