The Children's Commissioner for Wales has called for the education maintenance allowance (EMA) to be reviewed, claiming students find the grant system confusing and unfair.
In his annual report, Keith Towler said that a number of young people had contacted him complaining of "inequality" in the way the EMA is distributed, leaving many feeling concerned and upset.
His comments came as statistics revealed that thousands of students have still not received this year's grant.
Under the scheme, introduced in 2004, students aged 16-18 from low-income families can claim a cash grant of up to pound;30 per week to help them to continue their studies.
The allowance, paid fortnightly, is withdrawn if students do not attend lessons.
Applications in Wales have risen steadily year on year, from 26,655 in 200506 to 35,200 in 200809. In the last year, 32,700 (93 per cent) of applications were approved.
But the Children's Commissioner said he did not back the EMA concept.
"There should not be a reliance on such grants to ensure that young people remain engaged in education," he said.
"It would appear to me to be at odds with the aim of providing comprehensive educational opportunities to children that a system which causes so much concern to young people is in existence."
But the government said there were "diverse perspectives" on its effectiveness.
For example, the cross-party enterprise and learning committee heard a petition from a student arguing for widening the availability of the grant, while others have called for it to be reduced or removed because of the perception of inequality.
A spokesman said: "Our evaluation of EMA included focus groups of students, many of whom showed good understanding of the role of the scheme and understood its purpose to support students from poorer families."
However, the government is planning to consult on possible changes to the EMA and will consult young people on their views.
Meanwhile, Jenny Randerson, Liberal Democrat education spokeswoman, attacked the EMA as a "shambles" after new figures revealed that 5,500 students have still not received their grant for this academic year.
She accused education minister Jane Hutt of breaking the promise she made to the enterprise and learning committee in July that last year's backlog would be the last.
Ms Hutt promised to investigate this year's delays, having received assurances from the Student Loans Company, which administers the EMA, that students would not be put in the same situation as last year.
She said that while the SLC had streamlined the application process, she would be asking for a full report.
But she added: "There has been a welcome increase in the number of learners undertaking post-16 education. We need to recognise that this will create a pressure point on the system."