A recent campaign to recruit child psychiatrists received no applicants, according to the HSE.
Some teams in the child and adolescent mental health services are now seriously under-staffed.
The latest figures show that 1,724 children are waiting over three months to be seen.
The HSE said that all cases are triaged and urgent cases seen as a priority while those deemed to be routine are placed on a waiting list to be seen.
Many of these urgent cases are seen within days.
Seven in 10 young people whose referrals were accepted were seen within 12 weeks.