The majority of people listed by gardaí as still missing in 2005 are young foreign nationals.
Of the 18 people who went missing and remained missing last year, 16 are non-nationals and 12 of these are under 18 years of age.
The countries of origin of the missing minors include Nigeria, Sudan, Romania, Russia, Moldova and Somalia.
Children's rights groups have raised concerns in the past that some of the minors may have become victims of child trafficking or may have become involved in the sex trade in Ireland.
Among the missing are Olere Jane Abulume (14) from Nigeria, Faith Musa (15) from Sudan, Erna Isayeva (16) from Russia, Misha Rabu (16) from Moldova and Ivan Abrasouski (16) from Belarus.
A report by the Combating Paedophile Networks in Europe project in Cork said weaknesses in Irish legislation made it difficult for immigration officers to prove that trafficking takes place.
Rosanna Flynn, spokeswoman for Residents Against Racism, said she was concerned for minors seeking asylum who disappear in Ireland.
"I believe most of those non-nationals who are missing are on the run, but I don't rule out that they have become involved in the sex industry, trafficking or other inappropriate activities.
"Some of the Roma girls seem to disappear because they are married off as soon as they reach puberty, which is their custom. Other young people are desperate and are willing to go underground, travelling from one European country to another, to avoid being sent back to their own countries."
She said young people were particularly vulnerable, and she was aware of an African woman who, when she reached the age of 18 last year, was deported from Ireland and has since gone into prostitution.
"We do have a responsibility to these children who have been in our own education system and have been encouraged to have certain expectations. It is a measure of how unjust the asylum system is that they would think it is better to go on the run and take these risks than be deported."
